Compound Interest Calculator
See how your savings or investments could grow over time with compound interest. Enter your figures in the white box and the teal box will automatically calculate your estimated future value, contributions and interest earned.
How compound interest works
Compound interest is interest earned on both your original investment and previously accumulated interest. Over time, this can increase the growth of savings and investments.
This calculator estimates how an initial investment could grow with regular contributions and a constant annual interest rate.
What affects compound interest?
The main factors are your starting balance, regular contributions, annual interest rate, investment period and how frequently interest is compounded.
A longer investment period allows more time for compounding. Making additional contributions can also increase your final investment value.
How are contributions calculated?
Contributions are assumed to be made at the end of each contribution period. Interest is calculated using the selected compounding frequency.
When contribution and compounding frequencies differ, the calculator uses an equivalent effective interest rate for each contribution period.
Compound interest example
Suppose you start with $10,000, contribute $200 each month and earn an average annual interest rate of 7%, compounded monthly, for 20 years.
You would contribute $48,000 over the investment period, bringing your total invested amount to $58,000.
Your estimated future value would be approximately $129,000, with the remaining growth coming from compound interest.
Important considerations
Results assume a constant interest rate and do not account for taxes, fees, inflation or changing market conditions.
Investment returns are not guaranteed. Actual performance may be higher or lower than the calculator's estimates.