Skip to main content

Compound Interest Calculator

Calculate compound interest on any investment over time.


A compound interest calculator is an essential financial planning tool that shows how your money grows exponentially over time. Unlike simple interest, which only applies to your original principal, compound interest earns returns on both your principal and the interest already accumulated.

This snowball effect is the core mechanism behind long-term wealth building, retirement accounts, and investment portfolios. The longer your investment period and the more frequent the compounding, the more dramatic the growth becomes.

Use this free online compound interest calculator to model any investment scenario. Enter your starting amount, annual rate, time horizon, and compounding frequency to see your projected final balance, total interest earned, and a full year-by-year breakdown.