Compound Interest Calculator
The Compound Interest Calculator helps you estimate how your initial investment and recurring contributions could grow based on the interest rate, compounding frequency, and time period.
Investment Inputs
Contributions occur at period end. Daily compounding uses 365 periods per year. When frequencies differ, growth uses the equivalent contribution-period rate.
After 20 years
Detailed Breakdown
- Initial Investment
- —
- Additional Contributions
- —
- Total Contributions
- —
- Interest Earned
- —
- Ending Balance
- —
Growth Over Time
X-axis: Years · Y-axis: Balance
Year-by-Year Breakdown
Contributions include your initial investment and all deposits through each year. Interest earned is cumulative.
On smaller screens, swipe the table to see every column.
| Year | Contributions | Interest Earned | Ending Balance |
|---|
Estimates only. Actual investment returns are not guaranteed. This illustration assumes a constant rate and excludes taxes, inflation, fees, and withdrawals.
Understanding Compound Interest
Compound interest means earning interest on both your original investment and previously earned interest. Over time, this can help your balance grow, even without additional contributions. Our guide to simple interest vs compound interest explains how the two methods differ.
Use the calculator to compare different contribution amounts, interest rates, and time periods. If you are starting with a lump sum and do not plan to add more, set Additional Contribution to $0. The results assume a fixed rate; actual investment returns can vary.
For a quick estimate of how long an initial investment could take to double without additional contributions, explore the Rule of 72. For another official planning resource, visit the Investor.gov Compound Interest Calculator.
