Compound Interest Calculator
Free online compound interest calculator — see how your savings grow with regular contributions and compound interest over time.
How Compound Interest Works
Compound interest is interest earned on both the initial principal and the accumulated interest from previous periods. This creates a snowball effect where your money grows exponentially over time.
Where FV is the future value, P is the initial investment, PMT is the monthly contribution, r is the annual rate, n is the compound frequency, and t is the number of years.
The Power of Regular Contributions
Adding even small monthly amounts dramatically increases your returns. For example, $10,000 at 7% over 20 years grows to about $38,697 on its own — but with $500/month contributions, it grows to approximately $263,085.
Compound Frequency Matters
The more frequently interest compounds, the more you earn. Daily compounding yields slightly more than monthly, which yields more than quarterly or annually. However, the difference is modest compared to the impact of the interest rate and time period.