Our compound interest calculator is a free tool that helps you visualise how your money can grow over time. Whether you're planning for retirement, saving for a house, or just curious about the power of compounding, this tool gives you a clear, interactive picture of your financial future.
Simply enter your initial investment, any regular monthly contributions, an expected annual interest rate, and your time horizon — and the calculator does the rest, showing you a year-by-year breakdown of your balance, total deposits, and interest earned.
Compound interest is interest calculated on both your initial principal and the interest you've already earned. This means your money grows faster over time because each period you earn interest on a larger and larger balance — a concept often called "interest on interest."
For example, $10,000 invested at 7% annually becomes roughly $19,670 after 10 years and $38,700 after 20 years — nearly four times your original investment, without adding a single extra dollar. Add monthly contributions and the growth becomes even more dramatic.
Albert Einstein is often (apocryphally) credited with calling compound interest the "eighth wonder of the world." Whether he said it or not, the math speaks for itself.
This calculator is useful for anyone thinking about long-term saving or investing — from people just starting out who want to understand what's possible, to more experienced savers running scenarios for retirement planning, college funds, or investment accounts.