Interest, Loan and Investment Calculators
These calculators each apply one well-known formula and show the working: how a balance compounds, how a monthly SIP grows, what a loan's monthly instalment and total interest are, how much retirement needs and what return you actually earned. They are for savers, borrowers and DIY investors checking a bank quote, a fund statement or a homework problem.
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All Calculators (7)
Investment Calculator
Calculate investment returns and growthCompound Interest Calculator
Calculate compound interest and investment growthSimple Interest Calculator
Calculate simple interest on loans and investmentsInterest Calculator
Calculate various types of interestEMI Calculator
Calculate loan EMI and payment schedulesRetirement Calculator
Plan for retirement savings and expensesTime-Weighted Return Calculator
Time-weighted and money-weighted (XIRR) portfolio returns from your actual cash flows
Which tool do I need?
Compare simple and compound interest on the same deposit
Flip one switch to see what compounding adds, or apply the simple interest formula on its own with a year-by-year table.
Project savings with monthly deposits
Compound a starting balance daily to annually, add deposits on a schedule and see the year-by-year growth.
Choose between a SIP and a lump sum
Project the same money invested monthly or all at once and compare the amount paid in with the growth.
Work out a home or car loan EMI
Get the instalment, total interest and amortization schedule, then add insurance, tax and maintenance for the full monthly cost.
Estimate how much I need to retire
Compare projected savings with employer match against a target built from expenses, inflation and guaranteed income.
Calculate XIRR on a fund I have been buying into
Log each buy and sell with dates to get XIRR, and add share counts to unlock time-weighted return.
About Calculators
Pick by question. For growth, the Compound Interest Calculator handles any compounding frequency and regular deposits, the Simple Interest Calculator applies P x R x T / 100 for flat-rate loans and short deposits, and the Interest Calculator puts both behind one switch so you can see what compounding adds. The Investment Calculator compares a monthly SIP with a single lump sum. For debt, the EMI Calculator uses the reducing-balance method and lists ownership costs such as insurance and property tax separately from interest. The Retirement Calculator projects savings against an inflation-adjusted target, and the Time-Weighted Return Calculator reports net return, XIRR and time-weighted return from your own transactions.
Watch the units: EMI tenure and SIP duration are in months, the Interest Calculator's rate is always per year, and an APY quote already includes compounding. Projections use a constant rate with no volatility, taxes or fund charges, so subtract fees from the rate yourself. Five of these calculators keep inputs in the page URL, so a shared link reopens the same scenario. They explain the arithmetic and are not financial advice.
Guides
- How Compound Interest Works: Frequency, Deposits and the FormulaWhy 10% compounded monthly is not 10%, what A = P(1 + r/n)^(nt) really says, how deposits change the maths, and the mistakes that throw calculations off.
- SIP vs Lump Sum: What the Maths Says About Investing GraduallyHow SIP maturity is calculated, why a lump sum usually ends higher at the same return, and what that comparison leaves out about real markets.
- EMI and Loan Amortization: Where Each Payment GoesThe EMI formula worked through by hand, why early payments are mostly interest, how tenure and prepayment change total cost, and the flat-rate trap.
- Time-Weighted vs Money-Weighted Return (TWR vs XIRR)Two correct answers to "how did my investments do?". How TWR chains sub-period returns, how XIRR solves for a rate, and why they can disagree by tens of points.
Frequently asked questions
Which interest calculator should I use for a savings account?
The Compound Interest Calculator, set to the account's compounding frequency. Most savings accounts credit interest back into the balance, which is compound interest. If the bank quotes an APY or AER, enter it as an annual rate compounded annually, because that figure already includes compounding.
Why do two loan calculators give different monthly payments for the same rate?
Usually because one uses a flat rate and the other a reducing balance. A flat rate charges interest on the original amount for the whole term, which costs much more than the same number on a reducing balance. Rounding and whether fees are included also change the figure slightly.
How do I enter years when a calculator asks for months?
Multiply by 12. The EMI and Investment calculators take duration in months, so a 20-year loan is 240 and a 10-year SIP is 120. The Simple Interest Calculator works the other way and wants years, so 9 months is entered as 0.75.
What return rate should I assume in long-term projections?
Use a range rather than one number. Running a cautious, a middle and an optimistic rate, such as 5%, 7% and 9%, shows how sensitive the result is. Subtract fund fees and expected inflation if you want a figure closer to real spending power.
Is XIRR or time-weighted return better for judging my investments?
They answer different questions. XIRR measures how your own money did, including the timing of your deposits and withdrawals. Time-weighted return removes that timing and measures the fund itself, which is the fair way to compare it with an index or another fund.