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Compound Interest Calculator

Work out how much your money grows with compound interest. Enter a starting amount, monthly deposits, a rate and a time frame.

Compound interest is interest earned on interest. Each year your balance grows, and the next year you earn interest on the bigger balance.

This calculator shows the full picture. You get the final balance, the total you put in, and the interest that did the rest.

How it works

Start with the amount you have today. Add what you plan to deposit each month.

Enter the annual rate your account or investment pays. Pick how often it compounds, which for most savings accounts is daily or monthly.

The chart splits your balance into deposits and interest. Over long periods the interest slice becomes the bigger one.

The formula

A = P(1 + r/n)^(nt)

A = final amount, P = starting amount, r = annual rate as a decimal, n = compounding periods a year, t = years.

Tips

Frequently asked questions

What is the difference between simple and compound interest?

Simple interest is paid only on the original amount. Compound interest is paid on the original amount plus all the interest already earned.

How often should interest compound?

More often is slightly better. The gap between daily and monthly compounding is tiny, so the rate itself matters far more.

Does this include taxes?

No. Interest in a normal account is taxable, so your real result may be lower. Tax advantaged accounts like a Roth IRA avoid this.

This is not financial advice. Nothing on this site is investment, tax, legal or financial advice of any kind.

The calculators give simplified estimates from the numbers you enter. They ignore taxes, fees, rate changes and real market returns, and they can be wrong.

Do not make financial decisions based on these results. Speak to a licensed financial adviser, accountant or lender before acting, and read the full disclaimer.