Compound Interest Calculator
See how your savings grow over time with compound interest.
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About compound interest
- What is compound interest?
- Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. Unlike simple interest, which only applies to the original amount, compound interest causes savings to grow exponentially over time — often described as "interest on interest".
- How does compounding frequency affect growth?
- More frequent compounding means interest is added to your balance more often, which slightly increases the total amount earned. Daily compounding yields marginally more than monthly, which in turn yields a little more than annual compounding, assuming the same annual interest rate.
- What is the compound interest formula?
- The standard formula is A = P(1 + r/n)^(nt), where A is the final amount, P is the principal, r is the annual interest rate as a decimal, n is the number of compounding periods per year, and t is the number of years. In Advanced mode, enter the rate directly for the chosen period (e.g. a monthly rate when using monthly compounding). When regular contributions are included, each contribution is compounded from the point it is added.
- How do regular contributions help?
- Regular contributions dramatically accelerate wealth accumulation. Each contribution benefits from compound growth for the remaining investment period. Even small, consistent additions can outpace a large one-off deposit over a long time horizon due to the power of compounding. You can also enter a negative amount to model regular withdrawals.
- Is this calculator financial advice?
- No. This tool is for educational and illustrative purposes only. Results are projections based on the inputs you provide and assume a fixed interest rate with no taxes, fees, or inflation adjustments. Always consult a qualified financial adviser before making investment or savings decisions.