Compound Interest Calculator
Calculate compound interest with configurable compounding frequency and optional regular contributions.
Calculated locally in your browser. Nothing you enter is uploaded or stored.
- Free — no signup, no account, no watermark
- Runs entirely in your browser — nothing is uploaded to a server
- Works on mobile, tablet and desktop
- Instant — results appear as soon as you enter your input
Why this is private
- Calculated locally in your browser. Nothing you enter is uploaded or stored.
- Open your browser's DevTools → Network tab while using this tool — you won't see a request carrying your input, because it never leaves your device.
- Nothing you enter is uploaded to a server or shared with us — the processing happens entirely on your device.
Overview
Calculates how an investment or deposit grows when interest is added periodically and starts earning interest itself — including an optional additional contribution added at the end of every compounding period, for the common case of also topping up the balance regularly.
How to use it
- 1Enter the principal amount.
- 2Enter the annual interest rate.
- 3Choose a compounding frequency (annually, quarterly, monthly or daily).
- 4Enter the duration.
- 5Optionally enter an additional contribution added each period.
- 6View the final amount, with principal, contributions and interest earned broken out.
Formula
Compound interest
A = P × (1 + r/n)^(n×t)
P = principal, r = annual rate, n = compounding periods per year, t = years.
With a periodic contribution
A = P × (1 + r/n)^(n×t) + C × [((1 + r/n)^(n×t) − 1) / (r/n)]
C = contribution added at the end of each compounding period, on top of the principal's own growth.
Tips
- This calculator provides an estimate for planning purposes only and is not financial advice.
- More frequent compounding (daily vs. annual) yields slightly more return for the same nominal rate.
Frequently asked questions
What people use it for
Project a savings account or depositSee the balance after several years at a given rate and compounding frequency.
Model a savings plan with regular top-upsAdd a monthly or quarterly contribution to see the combined effect of a starting deposit plus ongoing saving.
Compare compounding frequenciesSee how much daily vs annual compounding adds for the same nominal rate.
Understand debt that compoundsThe same maths shows how an unpaid balance grows against you.
Sanity-check a 'guaranteed returns' pitchWork out what rate would actually be needed to hit a promised figure.
Related guides
- Reduce EMI or reduce tenure after a part payment: which saves more?Both lower your total interest, but not by the same amount. Here's the trade-off, a worked example, and how to compare your own loan.
- How to calculate a home loan foreclosure amountOutstanding principal, accrued interest, charges and tax — what goes into a loan foreclosure (pre-closure) figure, and why the bank's number can differ.
- How to calculate EMI (and why the formula looks so intimidating)A plain-English walkthrough of the EMI formula, what each variable means, and a worked example you can check by hand.
- SIP vs. lumpsum: what the math actually saysSystematic investing and lump-sum investing solve different problems. Here's how to reason about which one fits your situation.
Related tools
All finance toolsSimple Interest CalculatorSolve for interest, principal, rate or time — in years, months or days.SIP CalculatorProject the future value of monthly SIP investments, or compare against a lumpsum.FD CalculatorCalculate fixed deposit maturity value and interest earned.EMI CalculatorCalculate your monthly EMI, full amortization schedule, and part-payment or foreclosure savings.
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Compound Interest Calculator