About the Compound Interest Calculator
Use this calculator to estimate how an investment could grow when returns stay invested and generate further returns over time.
How to Use It
Enter the starting amount, estimated annual return, and investment length. Add a monthly contribution to model regular deposits, then choose how often the return compounds.
What Compound Interest Means
Compound growth applies returns to both your original investment and prior growth. Over longer periods, that compounding effect can become a large part of the final value.
Formula and Example
Without additional deposits, compound growth follows A = P(1 + r / n)^(nt), where P is the starting amount, r is the annual rate, n is compounding periods per year, and t is years. At 5% compounded annually, $1,000 becomes $1,050 after one year and about $1,276 after five years before fees or taxes.
Inflation-Adjusted Value
The inflation-adjusted value estimates future purchasing power using the inflation rate you enter. It helps distinguish a higher dollar balance from what that balance may buy in today's terms.
Important Limitation
Real investment returns vary and can be negative. Fees, taxes, timing, and market conditions are not included, so use this page for planning rather than as financial advice or a projected outcome.
Method, Limits, and Source
This model compounds the rate and contribution schedule you enter; it does not predict market performance. Investments can lose value, and past returns do not guarantee future returns. See the SEC's compound interest calculator and risk and return guidance before relying on a projection.