Free Compound Interest Calculator
Calculate how your investments grow over time with compound interest - often called the eighth wonder of the world. Supports annual, quarterly, monthly, and daily compounding frequencies so you can model real-world savings accounts, investment portfolios, and retirement accounts with precision.
How to Use
Enter your initial principal (starting balance), annual interest rate, time period in years, and select your compounding frequency. The calculator shows your total balance at maturity, the total interest earned, and a breakdown of contributions vs. growth.
Why Compounding Frequency Matters
The more frequently interest compounds, the faster your money grows. Daily compounding generates slightly more returns than monthly, which beats quarterly and annual compounding. For long-term investments spanning decades, even small differences in compounding frequency can result in thousands of dollars of additional growth.
Features
- Custom principal, rate, and time period - model any investment scenario from short-term savings to decades-long retirement planning
- Multiple compounding frequencies - choose from daily, monthly, quarterly, or annual compounding to match your actual accounts
- Interest earned and total growth display - see the breakdown between your original contributions and the growth generated by compounding
- Instant results - all calculations update in real-time as you adjust any parameter
Privacy
All calculations happen locally in your browser. No financial data is transmitted to any server.
Limitations and Financial Disclaimer
Compound-interest projections assume a fixed rate and regular compounding. Real investments fluctuate, fees reduce returns, taxes may apply, and savings accounts can change rates. Use this calculator for scenario comparison, not as investment advice or a promise of future returns.
Quick Answer
Compounding means returns are calculated on both the original principal and previously earned interest. Longer time horizons and consistent contributions usually matter more than small differences in compounding frequency.
Last reviewed: July 2026.