Compound Interest Calculator

Compound interest is what makes money grow faster over time than simple interest alone — instead of earning interest on just your original amount, you earn interest on your interest too, and that snowballing effect gets stronger the longer money is left to grow. This calculator shows exactly how a single starting amount compounds over time at a given annual rate.

The one input that makes this calculator different from a simple growth estimate is compounding frequency — how often interest is added to the balance. Choosing annually, semi-annually, quarterly, monthly, or daily compounding changes the result even at the exact same interest rate, because more frequent compounding means interest starts earning its own interest sooner. The difference is real but shrinks the more frequently you already compound — the jump from annual to monthly compounding matters far more than the jump from monthly to daily.

This tool models a single lump sum with no additional deposits along the way — it's meant to make the mechanics of compounding clear, not to replace a full savings or investment projection. The result is a mathematical projection based on the rate you enter, not a guaranteed return: real savings and investment rates change over time, so use this as an illustration of how compounding works rather than a promise of what you'll actually earn.