Compound Interest Calculator

See how compound interest grows your savings or investments over time. Add regular contributions and adjust the compounding frequency to model different scenarios.

How the compound interest calculator Works

This tool uses the following formulas to compute results:

  • A = P × (1 + r/n)^(n×t)
  • A = final amount, P = principal, r = annual rate, n = compounds/year, t = years
  • With contributions: A = P(1+r/n)^(nt) + PMT × [((1+r/n)^(nt) − 1) / (r/n)]

About Compound Interest Calculator

See how compound interest grows your savings or investments over time. Add regular contributions and adjust the compounding frequency to model different scenarios.

Use the inputs above to calculate your result instantly. Results update automatically as you type. All calculations happen in your browser, so your data is never sent to a server.

Frequently Asked Questions

What is compound interest?

Compound interest is interest calculated on the initial principal plus all accumulated interest. It causes your money to grow at an accelerating rate over time.

What compounding frequency is best?

More frequent compounding (daily or monthly) yields slightly more than annual compounding, but the difference is small compared to the interest rate itself.

How much should I invest monthly?

A common guideline is to save 15–20% of income. Even small consistent contributions grow significantly over decades thanks to compounding.

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