Compound Interest Calculator

See how your money grows over time with compound interest and regular contributions.

How to use

  • Enter your starting principal — the initial amount you're investing.
  • Set the annual interest rate (e.g., 7% for a stock market index fund average).
  • Choose how often interest compounds — daily and monthly are most common.
  • Set the number of years you plan to invest.
  • Add a monthly contribution to see the power of regular investing.
  • The Rule of 72 shows roughly how many years it takes to double your money.

About this Compound Interest

Use this free compound interest calculator to estimate future value from starting balance, interest rate, time, and contributions. It is useful for savings, investing, goals, and long-term planning. No signup is required, and the tool works on phones, tablets, and desktop browsers.