Compound Interest Calculator

See how savings grow when interest earns interest, with regular monthly contributions and the compounding frequency you choose.

See how money grows when interest earns interest. Enter a starting balance, a monthly contribution, an expected return and the number of years to project the future value and how much of it is growth rather than your own deposits.

Read the guide: How Compound Interest Grows Your Savings

Your savings plan

Compounding

Future balance

$144,573

After 20 years at 7%

You put in
$58,000
Interest earned
$86,573

Future balance

$144,573

  • Contributions40%
  • Interest60%

Assumes a steady return and on-time contributions. Real markets vary year to year. Estimates only, not financial advice.

How it works

  1. 1

    Set your starting point

    Enter what you have now and how much you add each month.

  2. 2

    Pick a return and term

    Choose an expected annual return, the number of years and how often it compounds.

  3. 3

    Watch it grow

    See the future balance and how much of it is interest rather than your own deposits.

Instant & 100% private — nothing is uploaded

Every calculation runs locally in your browser. The income, balances and goals you enter stay on your own device and are never sent to a server — nothing is stored, logged or shared.

Frequently asked questions

What is compound interest?
It is interest earned on both your original money and the interest already added. Over long periods this snowball effect does most of the heavy lifting.
How much does compounding frequency matter?
More frequent compounding helps a little, but the rate, the amount you contribute and the time invested matter far more.
Are real returns this smooth?
No. Markets rise and fall year to year. This assumes a steady average, which is useful for planning but not a promise of any single year.

Important

For information and planning only — not financial, tax or legal advice. These figures are estimates; rates, fees and rules vary, so confirm anything that affects a real decision with a qualified professional or the official source.

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