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Compound Interest Calculator

See how investments grow with compound interest and regular contributions. Yearly breakdown and effective annual rate.

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About the Compound Interest Calculator

Compound interest earns interest on previous interest, which makes time the most powerful factor in saving. Enter a starting amount, rate, period and compounding frequency, then add regular monthly, quarterly or yearly contributions to see your projected balance year by year.

How to use it

  1. Enter initial investment, interest rate and number of years.
  2. Choose compounding frequency and optional contributions.
  3. Review the future value and yearly growth table.

Good to know

  • Results are estimates for planning purposes and not financial, tax or legal advice. Lenders and tax authorities may calculate differently.
  • Investment returns are not guaranteed; past average returns do not predict future results.
  • Taxes and inflation are not included.

Frequently asked questions

What is the rule of 72?

Divide 72 by the annual rate to estimate the years needed to double: at 8%, about 9 years.

Does compounding frequency matter much?

A little: 7% compounded monthly is an effective 7.23% per year versus 7% compounded annually.

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