Compound Interest Calculator
See what a starting balance and a monthly contribution grow into once interest starts earning interest, with a year-by-year breakdown.
Finance Calculators
Work out what your money does over time: interest, savings, debt payoff, retirement targets and the household budget behind all of it.
20 free calculators
Finance & Personal Money
Work out what your money does over time: interest, savings, debt payoff, retirement targets and the household budget behind all of it.
Personal money splits into two questions that keep coming back: what will this grow into, and what is this costing me. Twenty calculators sit on this shelf because those two questions branch further than any other subject on the site.
The growth side starts with compound interest, which is the engine underneath almost everything else here. Add a time horizon and it becomes future value; run it backwards and it is present value; smooth a lumpy result into one annual figure and it is CAGR. Layer on a target income and an inflation assumption and you have the retirement calculator, which is really just compounding with a finish line.
The cost side starts with loan payment and credit card interest. Both turn a balance and a rate into a schedule, and both usually surprise people — a minimum payment on a card at 22% APR can stretch a modest balance across a decade. The debt payoff calculator takes several balances at once and shows what snowball and avalanche each cost in months and interest.
Between the two sit the housekeeping tools: the budget and 50/30/20 calculators for where the money goes, the emergency fund calculator for how much runway you have, the savings rate calculator for the single percentage that predicts how long you will need to keep working, and net worth for the number that actually tracks progress.
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All 20 finance calculators
Simple Interest Calculator
Calculate interest charged on the original principal only — the way short-term loans, some bonds and many promissory notes actually work.
Savings Calculator
Project a savings balance from a starting amount, a regular monthly deposit and an interest rate, and see how much of it is deposits versus interest.
Investment Return Calculator
Turn a start value, an end value and the money you added along the way into a total return and an annualised return you can compare fairly.
ROI Calculator
Measure return on investment as a percentage of what you put in, so a $400 gain on $2,000 can be compared with a $4,000 gain on $50,000.
Inflation Calculator
See what a sum of money will be worth after years of inflation, and how much you would need later to buy what it buys today.
Retirement Calculator
Compare the nest egg you are on track to build with the one your target retirement income needs, and see the gap in today's money.
Debt Payoff Calculator
Enter every balance, rate and minimum, add whatever extra you can afford, and compare snowball against avalanche month by month.
Loan Payment Calculator
Work out the fixed monthly payment on any amortising loan, plus total interest, total cost and a full payment schedule.
Credit Card Interest Calculator
Find out how many months a card balance takes to clear at your current payment, and what the interest costs you along the way.
APR Calculator
Fold origination fees and points into the quoted rate to get the annual percentage rate that lets you compare loan offers honestly.
APY Calculator
Convert a nominal rate and a compounding frequency into annual percentage yield, the number that makes two savings accounts comparable.
CAGR Calculator
Compress a lumpy multi-year result into one smoothed annual growth rate so different investments and business lines can be ranked.
Future Value Calculator
Project what a lump sum, a stream of payments, or both together will be worth at a chosen date and rate of return.
Present Value Calculator
Discount a future amount back to what it is worth today, the single idea behind valuing offers, settlements and investments.
Net Worth Calculator
Add up everything you own, subtract everything you owe, and see the one number that tracks financial progress better than income does.
Budget Calculator
Lay income against itemised spending to find your monthly surplus or deficit and see what share each category takes.
50/30/20 Budget Calculator
Split take-home pay into 50% needs, 30% wants and 20% savings, then check the split against what you actually spend.
Emergency Fund Calculator
Size a cash buffer from your real essential spending, then see the shortfall and how many months of saving closes it.
Savings Rate Calculator
Divide what you save by what you earn to get the percentage that predicts how many working years stand between you and financial independence.
How to choose the right tool
Three pairs get mixed up regularly, so it is worth being explicit.
Simple against compound interest. Use simple interest when the interest is charged on the original principal only — many short-term loans, some bonds, most promissory notes. Use compound interest when interest earns interest, which is every savings account and every investment. Over one year the difference is small; over twenty it is most of the money.
APR against APY. APR is what a loan costs you, including fees, expressed as an annual rate. APY is what a deposit earns you once compounding is folded in. Comparing a loan's APR with a savings account's APY is comparing two different conventions, and the difference is not decoration — a 12% nominal rate compounded monthly is a 12.68% APY.
ROI against CAGR. ROI tells you the total percentage gained and ignores how long it took. CAGR turns that into an annual rate, which is the only fair way to compare an investment held for two years against one held for nine. A 60% total return sounds excellent until you learn it took eleven years, at which point it is 4.4% a year.
If you are planning rather than measuring, start with the budget calculator. Almost every other tool on this shelf needs a monthly surplus figure as its input, and that is the one number most people have never actually worked out.
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Finance questions
Start with the retirement calculator, which compares the pot you are on track to build against the pot your target income needs. Then use the savings rate calculator to see whether the contribution it implies is realistic against your actual income.
Not automatically. Tax treatment varies by country, by account type and by income band, so building it in would make every result wrong for most visitors. Enter after-tax figures where a tool asks for income, and treat investment returns as gross unless you adjust them yourself.
There is no correct answer, which is why the field is yours to set. A common approach is to run the projection three times — pessimistic, expected and optimistic — and plan around the pessimistic one. The gap between a 5% and a 7% assumption over thirty years is roughly double the final balance.
Avalanche costs less: paying the highest interest rate first always minimises total interest. Snowball clears the smallest balance first, which costs slightly more but produces visible wins sooner. The debt payoff calculator shows both so you can see what the motivation is worth in money.
Some of them, yes — compound interest, loan payment, present value and ROI apply to any entity. For margin, break-even, unit economics and growth, use the business calculators instead, which are built around revenue and cost rather than personal cash flow.
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