Compound Interest Calculator
See how an initial amount plus regular contributions can grow over time with compound interest.
Value after 30 years
$252,111
Total contributed
$73,000
Interest earned
$179,111
About the compound interest calculator
Compound interest is the process of earning returns on both your original money and the returns it has already generated. Over long periods this creates an accelerating snowball effect, which is why starting to invest early is so powerful.
This calculator combines a one-off starting amount with regular monthly contributions, compounding monthly at the annual rate you choose. Adjust the inputs to see how contributions, rate of return and time each affect the final balance.
Frequently asked questions
How is compound interest calculated?
Each period, interest is added to your balance, and the next period's interest is calculated on that larger balance. This calculator compounds monthly and adds your monthly contribution at the end of each month.
Does this account for inflation or taxes?
No. The result is a nominal figure before inflation and taxes. To estimate purchasing power, use a rate of return net of expected inflation. This tool is educational and not financial advice.
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