Free online
calculators — fast & accurate.
Calculate scientific math, plan trades, SIPs and loans, convert currencies, and find your exact age with simple, fast and easy-to-use online calculator tools.
Tape
Enter equals · ⌫ delete · Esc clear · p π
Convert
CONNECTINGDate of birth
Your age, precisely
Position size
Decide how much to buy so one trade risks only the amount you choose.
FAQs
What risk percentage should I use per trade?
Most traders use 1% to 2% of their account value per trade. Lower percentages protect you during losing streaks, which are normal even for good strategies. Start at 1% until you have a track record you trust.
Does a wider stop-loss change my position size?
Yes. Position size equals your risk amount divided by the stop-loss distance, so a wider stop means a smaller position. This is the point of the calculation: the dollar risk stays the same no matter where you place your stop.
Why Position Size Matters More Than Picking Winners
Two traders can buy the same asset at the same price and get completely different results. The difference is often position size: one risks 1% of the account and takes the loss calmly, the other risks 20% and panics out. Your edge in trading comes as much from how much you risk as from what you pick.
Fixed-percentage position sizing makes your risk boring and predictable. A losing streak of ten trades at 1% risk costs about 10% of your account; the same streak at 10% risk nearly wipes you out. The calculator exists so this decision is automatic, not emotional.
The Position Size Formula, Explained
The formula is simple: shares to buy = (account size x risk %) / (entry price - stop-loss price). Everything else on the calculator is just arithmetic around this one line. The numerator is your dollar risk budget; the denominator is the risk per share.
For example, a $10,000 account at 2% risk gives a $200 budget. With entry at $40 and stop at $38, each share risks $2, so the answer is 100 shares. If the price hits your stop, the loss is $200 no matter how confident you felt about the trade.
Common Position Sizing Mistakes
The most common mistake is sizing by gut feel or round numbers, like always buying 100 shares. Round numbers ignore both your account size and your stop distance, so the risk drifts trade to trade. Another mistake is confusing position size with conviction: buying more because a trade feels certain just concentrates your risk.
A subtler mistake is forgetting that fees and slippage add to the loss. If your broker charges $5 per side, a $250 risk budget really becomes $240 of price risk plus $10 of costs. Subtract your round-trip fees from the risk amount before dividing, and your real risk will match the plan.
Profit & loss
Find your net profit or loss after fees on any trade.
FAQs
Should I include fees and commissions in my P&L?
Yes, always. Fees reduce every profit and deepen every loss, and ignoring them flatters your results. Enter commissions, spreads, and any platform fees so the net number reflects what actually lands in your account.
How do I calculate P&L as a percentage?
Divide your net profit by your total cost (entry price x quantity) and multiply by 100. A $480 profit on a $5,000 position is 9.6%. Percentages let you compare a $500 trade against a $50,000 trade on equal terms.
Gross Profit Is a Story; Net Profit Is the Truth
A trade that looks like a $500 win can really be a $480 win, or a $460 one if the fees are steep. On small accounts the gap between gross and net is the whole game: high fees can turn a break-even strategy into a losing one without you noticing.
Before entering any trade, subtract your round-trip costs from the expected gain. If a setup needs a $200 move to be worth it but costs $40 in fees, one-fifth of the move is already spoken for. Trade ideas that survive the fee check are the ones worth taking.
Using P&L to Review Your Trades
Most traders remember their winners and forget their losers. Logging the net P&L of every trade, fees included, gives you an honest record of what your strategy actually earns. Patterns show up fast: maybe your small positions carry you, or your losses cluster on a certain setup.
Review the log monthly and ask two questions: what is my average net profit per trade, and how many trades do I need for that average to mean something? A strategy with a $30 average net gain per trade needs very different sizing than one with a $300 average.
Why Percentages Beat Dollars for Comparison
A $500 profit sounds good until you learn the position was $100,000. In percentage terms it is 0.5%, barely more than noise. A $100 profit on a $500 position is 20%, a completely different outcome. Dollars describe the effect on your wallet; percentages describe the quality of the trade.
This matters most when comparing strategies or traders. One person making $2,000 a month on a $20,000 account is growing 10% a month; another making the same $2,000 on a $200,000 account is growing 1%. Same dollars, tenfold difference in skill. Always ask: percent of what?
Recurring investment growth
Estimate how a fixed monthly investment grows over time.
FAQs
What return rate should I assume?
Use a modest, long-term average for the kind of investment you plan to buy, and try a few rates to see the range. A diversified stock fund has historically averaged around 7% to 10% a year before inflation, but no future period is guaranteed to match the past.
Is it better to invest monthly or in one lump sum?
A lump sum invested earlier has more time to compound, so it usually wins on paper. But monthly investing is easier to sustain, spreads out market timing risk, and matches how most people earn money. Consistency beats perfect timing.
The Quiet Math Behind Monthly Investing
Monthly investing feels unremarkable: the same $500 leaves your account, month after month, for decades. But the math is anything but boring. In the $500-a-month example above, the last ten years of a thirty-year plan contribute most of the growth, because by then your earlier money is earning returns on top of returns.
This is why financial advice keeps repeating the same line: start early. A person who invests $500 a month from age 25 to 55 will typically end up with far more than someone who invests $1,000 a month from 45 to 55, even though the second person put in more money. Time does the heavy lifting.
Why Automatic Beats Willpower
The hardest part of monthly investing is not the math, it is the follow-through. Markets fall, bills pile up, and skipping one month feels harmless. But a skipped month is a month of compounding you never get back, and one skip makes the next one easier.
That is why automation matters more than motivation. An automatic transfer on payday turns investing into a default instead of a decision. You do not need discipline thirty years running; you need it once, on the day you set up the transfer.
Raising Your Amount as Income Grows
Most people start small and earn more later. Increasing your monthly amount by a little each year, say 5% or 10%, keeps your plan matched to your income and dramatically raises the final number. This is sometimes called a step-up plan, and it is the easiest upgrade to a basic monthly habit.
Run the calculator twice: once with your current amount, once with a yearly increase. The gap between the two totals is the price of standing still. Even a $25 monthly raise each year adds up to tens of thousands over a few decades, for almost no extra effort.
CAGR
The steady yearly rate that grows a start value into an end value.
FAQs
What is the difference between CAGR and average return?
An average of yearly returns ignores compounding, while CAGR includes it. If an investment gains 100% one year and loses 50% the next, the average return is 25%, but you are back where you started, so the CAGR is 0%. CAGR tells the truer story.
Can CAGR be negative?
Yes. If the end value is lower than the start value, the CAGR is negative, showing the steady yearly rate of decline. For example, $10,000 shrinking to $8,000 over 2 years is a CAGR of about -10.6%.
Why CAGR Beats Average Return
Average return is the number most people reach for, and it is often misleading. The classic trap: an investment rises 100% in year one and falls 50% in year two. The simple average is +25% a year, which sounds great. The reality is you have exactly what you started with, and CAGR correctly reports 0%.
The reason is compounding. Returns multiply, they do not add, so any honest multi-year rate has to be a geometric one. Whenever someone quotes a multi-year average, ask whether it is a CAGR. If it is not, the number is flattering the past.
CAGR in Plain English: The Formula
The formula looks intimidating but says something simple: find the total growth multiple, then spread it evenly across the years. The exponent (1 / years) is what spreads it. Without that step you would just have the total return, like 61% over five years, which tells you nothing about the yearly pace.
Try it on round numbers: $1,000 doubling to $2,000 in 10 years. The total multiple is 2, and 2^(1/10) - 1 is about 7.2% a year. That 7.2% is the famous doubling rate behind the rule of 72, which says money doubles in roughly 72 / rate years.
What CAGR Does Not Tell You
CAGR hides the ride. Two investments can share a 10% CAGR while one glides upward and the other crashes and recovers. The smooth number says nothing about the sleepless nights in between, so never judge risk from CAGR alone.
It also hides timing. A CAGR measured from a market low looks fantastic; measured from a peak, it looks terrible. Same investment, different start date, different story. When comparing CAGRs, always check that the time periods match, or the comparison is meaningless.
Loan EMI
Your fixed monthly payment for a loan at a given rate and term.
FAQs
Does a longer loan term always cost more?
The monthly payment drops, but the total interest rises, almost always by a lot. A 30-year loan can cost more than twice the borrowed amount in interest. Choose the shortest term whose payment you can comfortably afford.
Why is my early EMI mostly interest?
Interest is charged on the remaining balance, which is largest at the start. As each payment chips away at the principal, the interest portion shrinks and more of your fixed payment goes toward the balance. Making extra payments early cuts the most interest.
How a Loan EMI Is Actually Calculated
The EMI formula finds one number: the fixed monthly payment that pays off the loan exactly, interest included, by the last month. It depends on only three things: how much you borrow, the monthly interest rate, and the number of payments. Raise any one of them and the payment changes in a predictable way.
What surprises people is how the split works. On a 30-year loan at 6%, the first payment is about 83% interest and 17% principal. The bank gets paid first because the balance, and therefore the interest charge, is at its maximum. Understanding this makes the value of extra early payments obvious.
The Term Trap: Small Payment, Big Total
Lenders love to sell the monthly payment, not the loan. Stretching a car loan from 5 years to 7 years drops the payment and feels like a win, until you see the total interest. On $20,000 at 6%, the 7-year option adds roughly $1,500 in interest for a payment that is only about $70 lower.
The trap is psychological: monthly payments are vivid, totals are abstract. Always read the total repayment line before the payment line. If the longer term saves you $70 a month but costs $1,500 overall, you are buying convenience at a steep price.
Three Levers That Change Your EMI
You have exactly three levers: borrow less, get a lower rate, or shorten the term. Borrowing less means a bigger down payment or a cheaper purchase, which is the most powerful lever because it cuts both payment and interest. A lower rate usually means improving your credit or shopping multiple lenders.
Shortening the term is the lever people forget, and it is often the best deal. On that $300,000 example, moving from 30 years to 20 years at the same 6% raises the payment from $1,799 to about $2,150, but saves roughly $130,000 in interest. Run the numbers before you commit, and pick the shortest term you can sustain.
CD maturity
Project what a certificate of deposit earns at a fixed rate.
FAQs
What happens if I withdraw a CD early?
Banks charge an early-withdrawal penalty, typically forfeiting several months of interest, and on short CDs the penalty can eat into your principal. Only put money in a CD that you are confident you will not need before maturity.
Is the CD rate fixed for the whole term?
Yes. The rate is locked when you open the CD and does not change, even if market rates move. That is the appeal: a known return for a known period, with no surprises at maturity.
How a CD Grows Your Money
A CD is one of the simplest investments there is: you lend money to a bank for a fixed time, and the bank pays you fixed interest. There is no market to watch and no statement to decode. At the end of the term, you get your deposit back plus the interest, down to the cent, as the calculator shows.
That certainty is the whole product. A $10,000 CD at 4.5% for two years will be $10,920.25 at maturity whether the stock market soars or crashes. You trade the chance of bigger gains for the guarantee of a known outcome, which makes CDs ideal for money with a fixed purpose and date.
CD Ladders: A Simple Way to Stay Flexible
The classic complaint about CDs is the lock-in: your money is stuck for the whole term. A CD ladder solves this by splitting your deposit across several CDs with staggered maturities. Put $15,000 into three CDs of $5,000 each maturing in 1, 2, and 3 years, for example.
Every year one CD matures and you can spend it or roll it into a new 3-year CD at the current rate. Within a few years all your money earns long-term rates, yet some of it frees up every twelve months. You get higher yields without giving up all access.
CDs vs. Savings Accounts
A high-yield savings account and a CD often pay similar rates, so the choice comes down to flexibility versus certainty. Savings accounts let you withdraw anytime and their rates float with the market. CDs lock your money up but guarantee the rate for the full term.
If rates are falling, a CD wins: your rate stays put while the savings rate drops. If rates are rising, the savings account wins because you are not stuck. And for money you might need soon, an emergency fund belongs in savings, not in a CD with an early-withdrawal penalty.
Recurring deposit maturity
See what a fixed monthly deposit grows to with compound interest.
FAQs
How is the maturity value calculated?
The calculator adds up each monthly deposit and applies compound interest at the annual rate you enter, with quarterly compounding — meaning interest is calculated on the balance every three months.
What happens if I skip a month?
A missed deposit means less money in the account and less interest earned, and your maturity value will be lower than the calculator shows. Some banks also charge a small penalty for missed deposits.
Why Small Monthly Deposits Beat Occasional Lump Sums
Most people wait for "enough money" before they start saving, but a recurring deposit proves that consistency matters more than size. A $150 monthly deposit that never misses a beat will outgrow random $1,000 lump sums dropped in twice a year, because every month's deposit starts earning interest immediately.
The habit is the real product. Automating a fixed monthly amount removes the monthly debate about whether you can "afford to save this month" — the money moves before you can talk yourself out of it.
The Right Deposit Size for Your Budget
Pick a monthly amount you can sustain through tight months, not generous ones. A common guideline is to commit about 10–20% of your take-home income to savings, and a recurring deposit is an easy home for part of that — but an amount you keep skipping defeats the purpose.
Start conservative if you're unsure. You can always open a second recurring deposit or increase the amount later; what matters is building the unbroken streak that lets compounding do its work.
Short-Term vs Long-Term: Where Recurring Deposits Shine
Recurring deposits are ideal for goals one to five years out: an emergency fund top-up, a down payment, a wedding, or a planned purchase. The returns are predictable, so you know almost exactly what you'll have and when.
For goals decades away, growth-focused investing has historically offered more — but many savers use both: recurring deposits for the near-term goals they can't afford to miss, and investing for the far-off ones.
Percentage
Calculate X% of Y, reverse percentages, and percentage change instantly.
FAQs
How do I calculate percentage increase?
Use the % CHANGE mode: enter the old value and the new value, and the calculator shows the change as a percentage. A result of +15% means the number grew by 15%.
What is a reverse percentage?
It's finding the original number when you know the percentage and the result — for example, "I paid $110 after 10% tax; what was the original price?" Enter the result in X IS WHAT % OF Y mode, or simply divide $110 by 1.10 to get $100.
The Everyday Math That Saves You Money
Discounts, tips, and taxes all run on percentages, and doing them mentally keeps you from being fooled by marketing. A "$50 off" sign on a $400 item is 12.5% off — the same $50 on a $200 item is 25%. The dollar figure is identical; the deal is not.
Tipping is the same skill in reverse: 20% on a $65 bill is $13, and knowing that instantly beats fumbling with your phone while the server waits. Percentage fluency is small math with outsized daily value.
Percentages in Salary and Price Negotiations
A "3% raise" on a $60,000 salary is $1,800 a year — about $150 a month. Framing raises, rent increases, and fee changes as dollar amounts makes them concrete in a way percentages never are.
The same trick works when you're selling: quoting a price increase as "$12 more per month" lands very differently than "a 15% increase," even though they're identical. Whichever side of the table you're on, convert the percentage to dollars before you decide how to feel about it.
Why Percentage Points Are Not Percents
When an interest rate moves from 5% to 7%, that's a 2-percentage-point increase — but a 40% relative increase in the rate itself. News headlines often blur this distinction, and it matters: "loan rates up 40%" sounds catastrophic, while "rates up 2 points" sounds mild. Both describe the same change.
Whenever you see a percentage about a percentage, slow down and ask which base it's measured against. That single question cuts through most statistical spin you'll ever meet.
Days between dates
Count the exact number of days between any two calendar dates.
FAQs
Is the start date included in the count?
No — the calculator counts the days between the two dates, excluding the start date. January 1 to January 2 is 1 day.
Can I count days across different years?
Yes. Enter any two dates in any order across any years, and the calculator returns the exact number of days between them, including all leap days in between.
Where a Day Count Actually Matters
Most of the time, "about three months" is fine. But notice periods, late-payment penalties, subscription refunds, and contract deadlines run on exact days — and being off by two days can cost real money or a missed deadline. That's when a precise count stops being trivia and starts being protection.
Common triggers include rental agreements (30-day vs one-month notice differ), credit card grace periods, and return windows that count calendar days including weekends. When in doubt, count it exactly.
The Traps of Counting by Hand
Manual counting goes wrong in predictable ways: forgetting that February exists, assuming 30-day months, missing leap days, and the classic off-by-one error of counting both endpoints. Two people counting the same span routinely land on different numbers.
A calculator removes the ambiguity with one clear rule — exact calendar days, start date excluded — so both sides of an agreement get the same answer every time.
Planning Backwards From a Deadline
The calculator is just as useful in reverse: given a fixed end date, work out how many days you actually have to prepare. A "12-week" project starting mid-February doesn't have 84 days if holidays and weekends eat into it, but knowing the raw calendar span is the first step to a realistic plan.
Pair the day count with a simple milestone split — total days divided by the number of deliverables — and an intimidating deadline turns into a manageable daily pace.
Step-up investment
See how growing your monthly investment each year boosts long-term wealth.
FAQs
What is a good step-up percentage?
Many investors use 8–10% a year, roughly in line with typical salary growth. The best percentage is one you'll actually sustain — an optimistic 15% you abandon in year three beats no comparison to a steady 7% you keep.
Is step-up investing better than a flat monthly amount?
It builds a larger final value because you invest more dollars overall. But it only works if your income grows as assumed — during flat-income years, fall back to your base amount rather than pausing entirely.
Match Your Investing to Your Career Curve
Early-career savers face a frustrating math: the years when compounding matters most are the years they earn least. Step-up investing solves this by letting contributions start small and grow with income, capturing both the time advantage and the higher-earning years.
The rule is simple: every time your income rises, raise your investment by part of the raise. You never feel the pinch because you never had the money to spend, yet the final balance reflects decades of ever-larger contributions.
The Quiet Power of a 10% Annual Step-Up
A 10% yearly increase sounds aggressive until you see it in dollars: a $500 monthly investment becomes $550 in year two, $605 in year three — increments that usually vanish into normal salary growth. But over 20–30 years, that gentle slope roughly doubles the final value versus a flat contribution.
This is why "invest what you can and increase it yearly" beats agonizing over the perfect starting amount. The trajectory matters more than the starting point.
What If Your Income Doesn't Grow Smoothly?
Real careers have flat years, job changes, and pay cuts. A step-up plan survives them if you treat the increase as a target, not a contract: in lean years, hold the current amount steady rather than stepping down or stopping.
The worst outcome is abandoning the plan entirely during a rough patch — even a flat contribution keeps compounding alive. Automate the base amount and review the step-up once a year when you review your income.
Loan prepayment
See how extra payments cut your loan term and total interest.
FAQs
Does prepaying reduce my monthly payment or my loan term?
Usually it shortens the loan term while your scheduled payment stays the same — you finish earlier and pay less total interest. Some lenders offer the option to reduce the payment instead; ask which applies to your loan.
Is it always smart to prepay a loan?
Not always. If your loan rate is very low and you could earn more by investing, or if you'd drain your emergency savings to do it, holding the cash may be wiser. Prepayment shines most on high-rate debt.
Why Extra Payments Beat Higher Payments
You don't need to refinance or renegotiate to pay less interest — you just need to pay extra principal. Because interest is charged on the remaining balance, every extra dollar permanently reduces the base that future interest is calculated on.
The effect snowballs: the first extra payment saves a little interest, which means the next payment clears a little more principal, which saves a little more interest. Small, early extras compound in your favor exactly like investments compound — in reverse.
Lump Sum vs Monthly Extra: Which Wins?
A lump sum paid today always beats the same total spread over future months, because money applied now stops interest sooner. A $1,200 bonus paid this month saves more than $100 extra each month for a year.
But the best strategy is the one you'll repeat. If a bonus is uncertain, commit to the monthly extra; if the bonus lands, throw it at the principal too. Consistency plus windfalls is the fastest combination.
The Prepayment Checklist Before You Pay Extra
Three checks before you prepay: confirm there's no prepayment penalty, confirm extras are applied to principal (not advance payments), and confirm your emergency fund stays funded. Then target your highest-rate debt first — the math is unambiguous.
One exception: if your loan rate is below what you'd reliably earn elsewhere and you have no high-rate debt, investing the extra may leave you wealthier. Run both numbers before you decide.
Withdrawal plan
Plan steady monthly withdrawals from your investments over time.
FAQs
How much can I safely withdraw each month?
A common rule of thumb is around 4% of the starting balance per year (adjusted over time), which balances income against longevity. Use this calculator to test your specific numbers — the safe rate depends heavily on your expected return and time horizon.
What happens if my investments earn less than expected?
Lower returns mean withdrawals eat into principal faster, so the money may run out sooner than planned. That's why it's wise to test a conservative return rate and keep a cash buffer for down years.
Turning a Lump Sum Into a Paycheck
After years of building savings, the hardest question is how to spend them: too fast and the money dies before you do; too slow and you live below your means for no reason. A withdrawal plan converts the lump sum into a monthly paycheck with a defined lifespan.
The key insight is that the remaining balance keeps working. You're not just dividing $100,000 by the number of months — growth on the unspent portion can fund years of extra withdrawals, which is why the math surprises most people.
The Withdrawal Rate: The One Number That Rules Everything
Your annual withdrawal as a percentage of your starting balance determines everything. At 4–5% with moderate returns, most plans last decades; at 8–10%, even strong returns can't keep up and the balance collapses.
This is why the first withdrawal decision matters more than fine-tuning investments later. Set a sustainable rate up front, and give yourself a rule for adjusting it — like skipping inflation increases after a bad year.
Planning for the Years Returns Disappoint
Average returns hide ugly sequences: a few bad years early in your withdrawal plan do far more damage than the same bad years later, because you're selling while prices are down. This "sequence risk" is the main reason plans fail.
The defenses are simple: keep 1–2 years of withdrawals in cash so you never sell in a crash, test your plan at below-average returns, and build in flexibility to trim withdrawals temporarily. A plan with shock absorbers lasts; a rigid one breaks.
Lump sum growth
See how a one-time lump sum investment grows with compound returns over time.
FAQs
How is a lump sum different from monthly investing?
A lump sum is a single one-time deposit that grows entirely through compounding. Monthly investing adds new contributions over time, which can smooth out market timing but starts with less money at work. Many people do both - a lump sum plus regular monthly contributions.
What return rate should I assume?
It depends on where the money is invested. Conservative estimates might use 3-4% for savings-like products, while long-term stock market investors often model 6-8% average annual returns. Running the calculator with a low, medium, and high rate shows you the range of possible outcomes.
The Math Behind Lump Sum Growth
A lump sum grows according to the formula: future value = amount x (1 + rate)^years. The exponent is the key detail - returns compound on top of previous returns, so growth accelerates the longer the money stays invested. A calculator saves you from doing the exponentiation by hand and lets you test many scenarios quickly.
What surprises most people is how asymmetric the results are. Changing the time horizon by a few years moves the final number more than changing the return rate by a percentage point in many cases. Play with both inputs to build intuition for how compounding actually behaves.
Lump Sum vs. Staggering Your Investment
A common dilemma: you receive a bonus, inheritance, or sale proceeds - do you invest it all at once or spread it over several months? Investing the lump sum immediately gives your money the most time in the market, which historically produces the higher average outcome.
However, spreading purchases over time can feel less stressful if markets are volatile, since you avoid putting everything in right before a drop. If peace of mind matters more to you than maximizing expected value, splitting the lump sum into monthly investments is a reasonable middle ground.
Common Mistakes When Projecting Growth
The biggest mistake is treating the projected number as a promise. Real returns bounce around, fees eat into gains, and inflation reduces purchasing power. Always model a range of return rates rather than anchoring on a single optimistic figure.
The second mistake is ignoring what happens after the growth. If the goal is retirement spending or a house deposit, factor in how and when you'll actually withdraw the money - a lump sum that stays invested for 30 years behaves very differently from one you start drawing from in year 15.
Rent vs buy
Compare the true cost of renting a home versus buying one over your time horizon.
Loan tenure
Comparison horizon
FAQs
How long do I need to stay for buying to make sense?
There is no universal number - it depends on prices, rents, interest rates, and appreciation in your area. In many markets the breakeven falls between 5 and 10 years, but high-cost cities can push it beyond a decade. Enter your own numbers to find your personal breakeven.
Does the calculator include home maintenance and selling costs?
A good comparison must include them. Maintenance and repairs typically run about 1% of the home's value per year, and selling costs (agent fees, closing costs) often total 6-9% of the sale price. Leaving these out makes buying look better than it really is.
Why the Breakeven Year Is Everything
Buying a home front-loads your costs: down payment, closing fees, moving expenses, and immediate repairs all hit in year one. Renting spreads costs evenly. That imbalance is why short stays almost always favor renting - you simply don't own long enough for appreciation and principal paydown to offset the upfront hit.
The breakeven year is where the cumulative cost curves cross. Before it, renting is cheaper; after it, buying wins and the gap usually keeps widening. If your plans are uncertain, weight the scenarios by how long you realistically expect to stay, not by the rosiest case.
Rent Hikes Are the Silent Decider
Most rent-vs-buy comparisons hinge on one assumption: how fast rent rises. A $1,500 monthly rent growing 4% a year becomes about $2,220 in 10 years, while a fixed-rate mortgage payment stays flat. Even modest rent inflation compounds into a large advantage for owners over long horizons.
But the reverse is also true. In markets with rent controls, abundant new construction, or flat demand, slow rent growth extends the breakeven year dramatically. Use a rent growth rate that matches your city's history, not a national average.
The Non-Financial Factors That Tip the Scale
Money isn't the whole story. Buying locks in your housing cost and gives you control - no landlord decisions, no forced moves. For families valuing school stability or people who love customizing their space, that control has real value beyond the spreadsheet.
Renting, meanwhile, buys optionality: easy relocation for a job, no surprise $8,000 roof bill, and a down payment that stays invested and liquid. If your career or life is in flux, the flexibility premium of renting can outweigh a modest financial edge for buying.
Stock average price
Average your share cost across multiple purchases - total cost divided by total shares.
FAQs
How do I calculate my average share price?
Add up the total cost of every purchase (shares x price for each buy), add up the total number of shares, then divide total cost by total shares. If you paid brokerage fees, include them in the cost for a true average.
Is averaging down always a good idea?
No. Averaging down lowers your breakeven price, but it also concentrates more money in a stock that is falling - which can be throwing good money after bad if the company's fundamentals have deteriorated. Only average down when your original investment thesis still holds.
Averaging Down: How the Math Works
Averaging down means buying more shares at a lower price than your earlier purchases, which pulls your average cost per share down. If you own 100 shares at $50 and buy 100 more at $30, your average drops from $50 to $40 - so the stock only needs to recover to $40 for you to break even instead of $50.
The catch is position size: you've now doubled your money in a declining stock. The calculator shows you the new average instantly, but pair that number with an honest question - would you buy this stock fresh today at the current price? If not, averaging down may be hope disguised as strategy.
Averaging Up Is Underrated
Less discussed but often smarter: averaging up, or buying more of a stock that has risen. If your research was right and the price climbed from $50 to $70, adding shares raises your average cost - but it also increases your stake in a proven winner.
Many successful investors build positions gradually as a thesis plays out rather than going all-in on day one. The average cost calculator works the same way here: it tells you your new blended cost so you can judge the position's overall performance accurately.
Tracking Average Cost for Tax and Planning
Beyond strategy, average cost matters for record-keeping. When you eventually sell, your profit or loss is measured against what you paid - and with multiple purchases at different prices, the blended average is the baseline most investors track for planning.
Keep a simple log of every buy: date, shares, price, and fees. A calculator gives you the average in seconds, but the log is what lets you reconstruct your history months later when it's time to review performance or prepare records.
Inflation impact
See how inflation erodes purchasing power - what today's money is worth tomorrow.
FAQs
What inflation rate should I use?
Many planners use 2-3% as a long-term baseline, reflecting typical targets in major economies. For stress-testing, try 4-5% to see how your plan holds up if prices rise faster than expected. Historical averages for your country can ground the estimate.
Why does inflation matter for savings?
Because cash and low-interest savings often earn less than inflation, meaning their purchasing power shrinks each year. If your savings earn 1% while prices rise 3%, you're effectively losing 2% of buying power annually - which is why long-term money usually needs to be invested, not just saved.
The Quiet Tax on Idle Cash
Inflation is often called a silent tax because nobody sends you a bill - your bank balance stays the same while it buys less. At 3% annual inflation, money kept under the mattress loses half its purchasing power in about 24 years. Even "safe" savings accounts paying 1% interest are losing ground in real terms.
This doesn't mean holding cash is wrong - emergency funds need to be liquid and safe. But money you won't touch for 10+ years deserves a chance to outpace inflation, which is the fundamental argument for investing rather than hoarding.
Nominal vs. Real Returns: The Number That Matters
A 7% investment return sounds great until you subtract 3% inflation - your real return, the actual increase in buying power, is roughly 4%. Financial plans built on nominal returns overstate what you'll actually be able to afford.
Whenever you project long-term growth - retirement savings, education funds, a house deposit years away - run the numbers in today's dollars too. The inflation calculator makes this translation instant, turning impressive-sounding future totals into figures you can actually relate to your current budget.
How Inflation Changes Everyday Decisions
Inflation awareness improves small decisions as well as big ones. A fixed-rate loan becomes cheaper in real terms over time as your payments stay flat while wages and prices rise. Conversely, a long-term fixed income stream - like a set monthly payout that never increases - steadily loses value.
It also reframes "waiting to invest." Every year you delay, inflation has already taxed your uninvested cash. Time in the market isn't just about compounding gains; it's about stopping the guaranteed slow bleed of purchasing power.
Simple interest
Calculate simple interest: principal x rate x time, with total amount and breakdown.
FAQs
When is simple interest used instead of compound interest?
Simple interest appears in short-term personal loans, some auto loans, certain bonds that pay periodic coupons, and many textbook problems. Most savings accounts, credit cards, and mortgages use compound interest, so always check which method applies before comparing rates.
How do I handle periods shorter than a year?
Convert the time to years as a fraction: 6 months is 0.5 years, 90 days is roughly 90/365 = 0.247 years. Multiply principal x annual rate x that fraction. The calculator handles the conversion if you enter the period in months or days.
Simple vs. Compound: A Tale of Two Formulas
The difference between simple and compound interest is small at first and enormous eventually. On $10,000 at 8%, simple interest earns a flat $800 every year - $8,000 over a decade. Compounded annually, the same rate yields about $11,589 in interest over 10 years, because each year's gains join the principal.
This is why lenders and savers should both care: borrowers generally prefer simple interest (less total paid), while investors prefer compounding (more total earned). When comparing two products, make sure you're comparing the same interest type - or convert both to an effective annual figure.
Reading the Fine Print on Loans
A loan advertised with simple interest is refreshingly honest: you can verify every number with one multiplication. If a lender quotes a rate but the payments don't match the simple-interest math, compounding or extra fees are hiding somewhere in the terms.
Ask two questions before signing: is interest calculated on the original balance or the declining balance, and how often does it compound? The answers determine the true cost far more than the headline rate does.
Why Simple Interest Still Matters
In a world of compounding everything, simple interest remains the clearest mental model for interest itself. It isolates the pure cost of borrowing or reward for lending, free from the exponential curve that makes compound math harder to intuit.
It's also the right tool for short horizons. Over a few months, the difference between simple and compound is negligible, so the simpler formula gives quick, accurate-enough answers for deposits, bridge loans, and informal lending between friends and family.
Retirement savings
Project your retirement savings from monthly contributions, employer match, and growth.
FAQs
How does an employer match work?
Many employers add money to your retirement account based on what you contribute - for example, matching 50% of your contributions up to a limit. It's effectively a raise earmarked for retirement, and failing to contribute enough to earn the full match means leaving money on the table.
What return should I assume for retirement projections?
Long-term investors often model 5-7% average annual returns for a diversified portfolio after accounting for typical market history. Use conservative assumptions for planning - it's better to be pleasantly surprised than to fall short. Always run low, medium, and high scenarios.
Sales tax calculator
Add or remove sales tax (or VAT) from any price in seconds.
FAQs
How do I add sales tax to a price?
Multiply the price by one plus the tax rate as a decimal. For a $50 item at 6% tax: $50 × 1.06 = $53.00.
How do I find the pre-tax price from a total?
Divide the total by one plus the tax rate. A $215 receipt with 7.5% tax gives $215 ÷ 1.075 = $200.00 before tax, meaning $15.00 was tax.
US income tax calculator
Estimate your 2026 federal income tax by filing status, with marginal vs effective rate.
FAQs
What is the difference between marginal and effective tax rate?
Your marginal rate is the rate applied to your last dollar of income — the bracket you fall into. Your effective rate is total tax divided by total income, and it is always lower because earlier dollars were taxed at lower rates.
Does this include state income tax?
No. This estimates federal income tax only, using the 2026 IRS brackets and standard deduction. State taxes vary widely — nine states have no income tax at all, while others add their own brackets on top.
How the 2026 Federal Brackets Work
The US taxes income progressively across seven brackets: 10%, 12%, 22%, 24%, 32%, 35% and 37%. For 2026, a single filer pays 10% on the first $12,400 of taxable income, 12% up to $50,400, 22% up to $105,700, and so on. Married couples filing jointly get roughly double the thresholds.
The key insight: moving into a higher bracket never taxes your whole income at the higher rate — only the dollars above the threshold. Earning more always leaves you with more after tax.
Standard Deduction vs Itemizing
For 2026 the standard deduction is $16,100 (single), $32,200 (married filing jointly) and $24,150 (head of household). You subtract it from income before brackets apply. Itemizing only beats it if your mortgage interest, state taxes and charitable gifts add up to more.
Most filers take the standard deduction — it is simpler and, since the 2017 tax changes roughly doubled it, usually the better deal.
Why Your Refund Is Not a Bonus
A tax refund just means you overpaid through withholding during the year. Getting $2,400 back feels good, but it was an interest-free loan to the government. Adjusting your W-4 withholding puts that money in each paycheck instead, where it can earn interest or pay down debt.
Use this calculator with different income figures to see how a raise or bonus actually flows through to your take-home pay.
Mortgage calculator
Monthly payment, total interest and a yearly amortization schedule for any home loan.
FAQs
What is amortization?
Amortization is the process of paying off a loan in fixed installments where each payment is split between interest and principal. Because interest is charged on the remaining balance, early payments are interest-heavy and later payments are principal-heavy.
Is a 15-year or 30-year mortgage better?
A 15-year loan has much higher monthly payments but far less total interest and usually a lower rate. A 30-year loan costs more overall but keeps payments — and risk if income drops — lower. Compare both with this calculator before deciding.
The True Cost of a Mortgage
On a 30-year loan, total interest can exceed the amount borrowed. A $320,000 loan at 6.5% costs about $408,000 in interest over 30 years. At 5% it costs about $298,000 — a single percentage point saves over $100,000. Small rate differences compound enormously over decades.
This is why shopping for rates, improving your credit score before applying, and considering a larger down payment pay off far more than most people expect.
Why Extra Payments Are So Powerful
Because early payments are mostly interest, any extra principal payment now avoids interest on it for the rest of the loan. Paying just $200 extra per month on the example above cuts roughly 7 years off the term and saves about $120,000 in interest.
Even one extra payment per year — or rounding your payment up to the next $100 — makes a visible dent. Check your loan allows penalty-free overpayments first.
PITI: The Payment Beyond the Payment
Lenders quote principal and interest, but your actual monthly housing bill is PITI: principal, interest, property tax and insurance. Tax and insurance are often collected monthly into escrow and can add 30–50% on top of the P&I figure.
With less than 20% down, most loans also add private mortgage insurance (PMI) until you reach 20% equity. Budget on PITI, not just the calculator's headline number.
Tip calculator
Tip amount, total bill and per-person split for restaurants — 15%, 18%, 20% presets.
FAQs
Should I tip on the pre-tax or post-tax total?
Pre-tax is the standard convention — tip on the food and drink subtotal before sales tax is added. The difference is small on one meal but it is the technically correct base.
How much should I tip for delivery or takeout?
For restaurant delivery, 15–20% is customary (a few dollars minimum for small orders). For counter takeout where you just pick up a bag, tipping is optional — 10% or a dollar or two is a kind gesture but not expected.
Why Tipping Percentages Keep Creeping Up
The old standard was 10%, then 15%, and now 18–20% is the norm in most US cities — with some prompts suggesting 25–30%. The shift reflects stagnant tipped wages: the federal tipped minimum wage has been $2.13/hour since 1991, so tips are most of a server's income.
Knowing the history helps you tip deliberately rather than guiltily — pick your percentage by service quality and move on.
The Math Trick Servers Hope You Know
To find 20% fast, move the decimal one place left and double it: 20% of $64.50 is $6.45 × 2 = $12.90. For 15%, take 10% and add half again: $6.45 + $3.23 = $9.68. Or just use this calculator and skip the arithmetic entirely.
Rounding the total to a clean number after tipping also makes splitting painless — $76.11 becomes $76 or $77 without anyone caring.
Tipping Around the World
US tipping culture is the outlier. In Japan and South Korea, tipping can offend. In most of Europe, 5–10% or just rounding up is plenty since service is included. In the UK, 10–12.5% is standard when service is not included.
If you travel, check local norms before you go — this calculator's customs assume North American conventions.
BMI
Calculate your Body Mass Index from height and weight.
FAQs
What is a healthy BMI?
A BMI between 18.5 and 24.9 is classified as the healthy range. It is a screening tool, not a diagnosis — muscle mass, age, and body composition can all shift what a given BMI means for you.
Does this calculator work with feet, inches, and pounds?
Yes. Enter your height in inches and weight in pounds, and the imperial formula (with the 703 factor) is applied. You can also use centimeters and kilograms for the metric formula — both give the same result.
What BMI actually measures
BMI is a ratio of weight to height, and nothing more. It does not know whether the weight comes from muscle, bone, or fat, which is why very athletic people can land in the "overweight" band while being perfectly fit.
Treat it as a first-pass screening number. If it puts you in a category that surprises you, look at waist size, activity level, and how you feel before drawing conclusions.
Why the 18.5 to 24.9 band matters
Large population studies link the 18.5–24.9 range with the lowest average health risks, which is why it is labeled "healthy." Risk tends to rise as BMI moves well above or below that band.
Still, averages are not individuals. Someone at 25.5 who exercises daily may be healthier than someone at 22 who does not — use the band as a reference point, not a verdict.
Making the number useful
Recalculate every few months rather than daily; BMI moves slowly and daily noise is meaningless. Log it alongside habits — sleep, steps, meals — so you can see what actually shifts the number.
If your BMI sits outside the healthy range and stays there, that is simply information worth acting on. Small, steady changes in diet and movement move BMI more reliably than crash efforts.
BMR & calorie needs
Estimate your Basal Metabolic Rate — calories burned at rest.
FAQs
What is the difference between BMR and TDEE?
BMR is the calories you burn at total rest. TDEE (total daily energy expenditure) adds everything else — walking, working, exercise, even digesting food. Multiply BMR by an activity factor (roughly 1.2 to 1.9) to estimate TDEE.
Does BMR change with age?
Yes, it slowly declines with age, mainly because muscle mass tends to decrease. The Mifflin-St Jeor equation subtracts 5 calories per year of age, so strength training that preserves muscle is the main way to slow the decline.
Your body burns most calories doing nothing
For most people, BMR accounts for roughly 60–75% of all calories burned in a day. Keeping your heart beating, lungs breathing, and brain running is genuinely expensive in energy terms.
That is why crash diets backfire: cutting far below BMR signals the body to conserve energy, making further loss harder and rebound likelier.
Muscle is the biggest lever you control
Muscle tissue burns more calories at rest than fat tissue does. Two people with the same weight can have BMRs hundreds of calories apart depending on body composition.
This is the real reason strength training helps with weight management — it raises the floor of what you burn all day, every day, not just during the workout.
Using your BMR number wisely
Multiply your BMR by an honest activity factor to estimate daily needs, then adjust food intake in small steps — 200 to 300 calories at a time — and watch the trend over two to three weeks.
If the scale is not moving, recheck portion sizes before cutting further. Going below BMR for long stretches is rarely sustainable and often counterproductive.
Ideal weight
Find a healthy target weight range for your height.
FAQs
Which ideal weight formula is most accurate?
None is exact — Devine, Robinson, Miller, and Hamwi all estimate from height alone. The BMI-based range (18.5–24.9) is usually the most practical target because it gives a zone rather than a single number.
Can I use inches and pounds with this calculator?
Yes. Enter your height in inches and results are shown in pounds; use centimeters and results come out in kilograms. The formulas work the same in either system.
There is no single "ideal" number
Every ideal-weight formula is a statistical estimate built from averages. Real bodies vary in bone structure, muscle, and proportions, so two people at the same height can be healthy at quite different weights.
That is why ranges beat targets. A 10–15 kg healthy band for a given height is more honest than a single decimal-point number.
Why the old formulas still get used
Formulas like Devine date back decades and were originally built for medicine dosing, not fitness goals. They survive because they are simple and roughly right for average frames.
The BMI range adds the missing piece — an upper and lower bound — so you can aim for a zone instead of chasing one magic number on the scale.
Turning a range into a plan
Pick the middle of the range as your first target, then reassess how you look, feel, and perform when you get there. You may find your personal sweet spot sits above or below the midpoint.
Move toward it gradually: a steady 0.5 kg per week beats aggressive cuts that cost you muscle. The range will still be there when you arrive — it is a destination, not a deadline.
Water intake
Estimate your daily water intake from weight and activity.
FAQs
Is 8 glasses of water a day really the rule?
Eight 8-oz glasses (about 2 liters) is a decent average, but needs vary a lot with weight, activity, and climate. A personalized estimate based on your weight is more useful than a one-size number.
Can I drink too much water?
Yes, though it is rare. Drinking far more than you need in a short time can dilute blood sodium (hyponatremia). Stick near your calculated target, drink to thirst on top of it, and spread intake through the day.
Why the "8 glasses" rule is only a starting point
The 8-glasses guideline assumes an average adult and average conditions. A 55 kg office worker and a 95 kg construction worker in summer heat have very different needs, which is why a weight-based estimate beats a flat rule.
Use the flat rule as a floor, not a ceiling. If you are larger, active, or somewhere warm, your real target is higher.
Activity changes everything
An hour of hard exercise can cost you 500 ml to over a liter of sweat. That is why the calculator asks about activity level — sedentary and very active people can differ by a liter or more per day.
A simple habit: drink a glass before and after workouts, and keep water visible during the day. Most shortfalls come from forgetting, not from needing exotic hydration strategies.
Signs you are getting it right
Pale yellow urine, steady energy through the afternoon, and rarely feeling very thirsty are all good signs. Dark urine, headaches, and dry mouth suggest you are running behind.
Do not chase a number obsessively — adjust up on hot or active days, ease off when you are less active, and let the calculator's target be your anchor.
All calculators
Every calculator also has its own page with a step-by-step guide.
Money guides
Short, practical guides that pair with the calculators above.