Compound Interest Calculator

Compound interest is interest calculated on both your original deposit (the principal) and the interest already added. Because each period earns interest on a larger balance, growth accelerates over time — the longer the money compounds, the more pronounced the effect.

More frequent compounding (monthly or daily vs. annually) adds interest to the balance sooner, so the next period earns slightly more. The difference is modest at typical rates but grows with higher rates and longer time horizons.

Adding a fixed amount on a regular schedule — monthly or annually — steadily increases the balance that earns interest. Over long periods, consistent contributions often matter more than the interest rate itself, because they keep enlarging the principal that compounding acts on. Monthly contributions of a given annual total finish slightly ahead of one yearly deposit because each instalment starts compounding sooner.