Compound Interest Calculator
See how savings grow with compound interest and monthly contributions — final balance, interest earned and a year-by-year table.
Enter a starting amount, rate and number of years to see your growth.
For planning only — real returns vary and taxes and fees are not included. Calculated in your browser; nothing is sent to a server.
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How to use this tool
- 1Enter your starting amount and how much you will add each month.
- 2Enter the expected annual interest rate or return.
- 3Choose the number of years and how often interest compounds.
- 4See your future balance, and open the year-by-year table.
Features
- Starting balance plus optional monthly contributions.
- Monthly, quarterly, annual or daily compounding.
- Splits the result into money you put in and interest earned.
- Year-by-year growth table up to 100 years.
Privacy
Your numbers stay in your browser. Nothing is sent to a server.
Frequently asked questions
What is compound interest?
Interest earned on both your original money and the interest it has already earned, so growth speeds up over time.
What is the Rule of 72?
Divide 72 by the yearly rate to estimate how many years it takes to double your money: at 6%, about 12 years.
When are contributions added?
At the end of each month. The chosen compounding frequency is converted to an equivalent monthly rate.
Is this a guaranteed return?
No. Savings accounts have a stated rate, but investment returns vary year to year. Taxes, fees and inflation are not included.
Guides
- New Year Savings Goal: How Much to Save Each Month
Turn a New Year savings resolution into a monthly number. The formula, worked examples with interest, and a free compound interest calculator.