About Compound Interest Calculator
This compound interest calculator estimates how a balance can grow over time. Enter a starting amount, a monthly contribution, an annual interest rate and the number of years, then choose how often interest compounds: monthly, daily, quarterly or yearly. It shows the final balance, the total you contributed and the interest earned, with a year-by-year table.
Contributions are added at the end of each month, and the annual rate is treated as a nominal rate converted to an equivalent monthly rate for the chosen compounding. Real returns vary, fees and taxes are not included, and the result is an estimate for information only, not financial advice or a promise of returns. Your inputs never leave your browser.
How to use Compound Interest Calculator
- 01
Enter your starting amount and monthly contribution.
- 02
Set the interest rate and years.
- 03
View the final balance and yearly growth.
When to use it
- Estimate how a savings account might grow with regular monthly deposits.
- See how much of a final balance is your contributions versus interest.
- Compare monthly, daily, quarterly and yearly compounding for the same rate.
- Test how starting earlier or contributing more changes the final amount over time.
- Plan a long-term goal, such as a deposit or education fund, with rough numbers.
Frequently asked questions
What is compound interest?
Compound interest is interest earned on both your original money and on interest already added. Because each period's interest is added to the balance, growth speeds up over time compared with simple interest.
How does the calculator work out the final balance?
It converts the annual rate to an equivalent monthly rate for the chosen compounding, then, month by month, grows the balance and adds your contribution at the end of the month, until the years are finished.
Does compounding frequency make a big difference?
Usually only a small one at the same rate. Daily compounding yields slightly more than yearly. The rate, the time and the amounts you add each month tend to matter far more.
Are taxes, fees and inflation included?
No. The calculation assumes a constant rate with no fees, taxes or inflation, so real results will differ. Use it as a rough estimate for information, not as financial advice or a forecast.
Can I leave the monthly contribution at zero?
Yes. Set the monthly contribution to 0 to see how a single starting amount grows alone. You can also set the starting amount to 0 and rely only on monthly contributions.
Is my financial data saved?
No. Everything is calculated in your browser, and the amounts you enter are not uploaded or stored anywhere. There is no sign-up. Results are estimates for information only, not financial advice.