Finance

📈 Compound Interest Calculator

See how a starting balance, monthly deposits and compound interest grow over time — including a year-by-year breakdown of contributions versus interest.

—Future balance
—Total deposits
—Interest earned
DepositsInterest
YearBalanceDeposited so farInterest so far

Projection only — real returns vary. Interest is compounded at the selected frequency and deposits are added monthly.

About the Compound Interest Calculator

Compound interest is the engine of long-term wealth: at a 7% annual return, money roughly doubles every 10 years, and the majority of a 30-year saver's final balance comes from interest, not deposits. The best way to feel that is to move the sliders and numbers yourself.

This calculator converts your nominal annual rate into an equivalent monthly rate based on the compounding frequency you choose, adds your deposit every month, and tracks the balance year by year so you can see exactly when interest starts doing the heavy lifting.

Frequently asked questions

What is compound interest?

Compound interest is interest earned on interest. Each period, your interest is added to the balance, and the next period's interest is calculated on the bigger balance. Over decades this snowball effect can outgrow your own deposits.

Which compounding frequency should I choose?

Pick the one your bank or investment actually uses — savings accounts usually compound monthly or daily, many bonds annually. More frequent compounding yields slightly more at the same nominal rate.

Is this the same as my real investment return?

No — it is a smooth projection at a constant rate. Real markets go up and down. Use it to compare scenarios (for example, 5% vs 8%, or 10 vs 20 years), not as a promise.