Use this compound interest calculator to estimate how a starting balance, regular contributions, an assumed interest rate, and time could affect future value.
Change the inputs to compare scenarios and see how much of the projected balance comes from money you contributed versus estimated compound growth.
What Compound Interest Means
Compounding occurs when interest is added to a balance and future interest is then calculated on both the original money and previously credited interest.
This calculator uses a simplified model in which the interest rate remains constant and your regular contribution is added at the end of each selected compounding period.
When to Use This Tool
- To compare different starting balances or contribution amounts.
- To see how a longer or shorter timeline changes a projection.
- To compare different assumed annual interest rates.
- To estimate how much projected growth comes from contributions versus interest.
- To test a savings or long-term growth scenario before committing money.
Compound Interest Growth Calculator
Enter a starting balance and choose how often interest compounds and a regular contribution is added.
| Year | Money Contributed | Estimated Balance |
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Contributions are assumed to occur at the end of each selected period. The annual rate is assumed to remain constant for the full timeline.
How to Read Your Result
Estimated Final Value is the projected ending balance produced by the assumptions you entered.
Total Money Contributed includes your starting amount plus every regular contribution added during the projection.
Estimated Interest is the difference between the projected ending balance and the total amount contributed.
A larger projected value does not automatically mean a financial product is better. Higher expected returns can involve different levels of risk, fees, restrictions, or uncertainty that this calculator does not measure.
What Assumptions Does This Calculator Make?
The calculator assumes a fixed annual rate for the entire period, no withdrawals, no taxes or fees, and regular contributions made at the end of each selected period.
It also assumes that the contribution frequency and compounding frequency are the same. For example, selecting monthly means interest is compounded monthly and the entered contribution is added once each month.
Real savings accounts and investments may calculate interest, contributions, dividends, fees, and returns differently.