How to Calculate Simple and Compound Interest

Why interest math is easy to misestimate

Compound frequency and time period dramatically change outcomes. A calculator shows the difference between quoted rates and real growth.

Common use cases

Compare savings accounts, estimate loan costs, teach finance concepts, and plan fixed-deposit maturity values.

How to use the Interest Calculator

Enter principal, rate, time, and compounding interval, then review total interest and final balance.

Privacy-first finance tools

Account balances and loan amounts stay on your device during calculations.