Compound Interest Calculator

Calculate compound interest with optional monthly contributions. See future value, total interest earned, and a year-by-year breakdown.

Frequently Asked Questions

How do I calculate compound interest online?
Enter your principal amount, annual interest rate, compounding frequency, and time period. Click Calculate to see your future value, total interest earned, and a year-by-year growth breakdown instantly.
What is the difference between monthly, quarterly, and annual compounding?
Compounding frequency determines how often interest is calculated and added to your balance. Monthly compounding (12x/year) yields slightly more than quarterly (4x/year) or annual (1x/year) because interest earns interest more frequently.
How do monthly contributions affect compound interest growth?
Regular monthly contributions significantly accelerate wealth growth because each deposit starts earning compound interest immediately. Even small consistent contributions can outpace a large initial investment over time.
Is my financial data safe with this compound interest calculator?
Yes. All calculations happen entirely in your browser. No data is ever sent to a server.