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Compound Interest Calculator
See how money grows with compound interest and regular monthly deposits, year by year.
Balance after 20 years
| Year | Contributed | Interest | Balance |
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How it works: interest is added at the chosen compounding frequency and your monthly contribution is added at the end of each month. The more often interest compounds, and the longer you leave it, the more of the final balance comes from interest rather than from what you put in. Returns aren’t guaranteed — for investments, try a few different rates to see a range.
About the Compound Interest Calculator
The Compound Interest Calculator shows how savings or investments grow when interest earns interest. Enter a starting amount, a monthly contribution, the annual rate and the number of years, choose daily, monthly, quarterly or yearly compounding, and see the final balance, how much you put in and how much came from interest, with a year-by-year table.
How to use the Compound Interest Calculator
- Enter your starting amount and monthly contribution.
- Enter the annual interest rate and number of years.
- Choose how often interest compounds.
- Read the final balance and check the year-by-year table.
Frequently asked questions
What is compound interest?
Compound interest is interest earned on both your original money and the interest it has already earned, so growth speeds up over time.
How often should interest compound?
More frequent compounding earns slightly more — daily beats yearly — but the rate and the time you stay invested matter far more.
What is the rule of 72?
Divide 72 by the annual rate to estimate how many years money takes to double. At 8%, that is about 9 years.