Simple & Compound Interest Calculator
Enter your principal amount, annual interest rate, and time period to calculate both simple and compound interest side by side, so you can compare the difference directly.
Frequently Asked Questions
What's the difference between simple and compound interest?
Simple interest is calculated only on the original principal for the whole period. Compound interest is calculated on the principal plus any interest already added, so it grows faster the longer the time period and the more frequently it compounds.
Does compounding frequency make a real difference?
Yes, though usually a modest one — monthly compounding earns slightly more than annual compounding at the same nominal rate, since interest starts earning its own interest sooner.