Compound Interest
See how your savings grow with compound interest — regular deposits, any compounding, yearly step-up, inflation and tax — or find the saving, time or rate you need for a goal.
- Your data never leaves your device
- 100% free
- No sign-up
- Works offline after first load
How to calculate compound interest
- Enter your starting amount, regular contribution, interest rate and years.
- Choose the compounding frequency and when you deposit; add inflation, tax or a yearly step-up.
- See the future value, interest earned, a year-by-year chart and table — or switch mode to plan a goal.
About Compound Interest Calculator
Watch your money grow. Start with any amount, add regular monthly or yearly contributions and see the future value, how much you put in and how much came from interest — with a chart and a year-by-year table.
Choose how often interest compounds, whether you deposit at the start or end of each period, and increase your contributions every year. Inflation shows what the result is worth in today’s money and tax on gains gives the net figure. Planning a goal? Find the monthly saving, time or return you need.
Good for
- Savings and investment planning
- Retirement and education goals
- Comparing compounding frequencies and rates
Tip: Starting early matters more than the rate — compare 10 and 20 years with the same saving.
Frequently asked questions
What is compound interest?
Interest that is added to your balance and then earns interest itself. Over long periods this “interest on interest” makes savings grow much faster than simple interest.
How often should interest compound?
The more often, the more you earn — daily beats yearly — but the difference is small. The effective annual rate shows the true yearly growth for each choice.
Can I work out how much to save each month?
Yes — choose “Saving needed”, enter your goal and the years, and the calculator finds the monthly amount. “Time to goal” and “Rate needed” solve the other way round.
What is a step-up?
Raising your contribution by a percentage every year, e.g. 10% as your income grows. It can make a big difference over 10–20 years.
Can I save or share a calculation?
Yes — click Share to copy a link that opens the calculator with your numbers, Print / PDF to save the results, or open History to go back to recent calculations.
Is my data stored or sent anywhere?
No. Everything is calculated in your browser. Your recent calculations are kept only in this browser (History), and a shared link contains just the numbers you entered.