Compound Interest Calculator
Estimate investment growth, final balance, total contributions and interest earned with compound interest and optional monthly contributions.
Compound interest calculator
Estimate investment growth with compound interest and optional monthly contributions.
Final balance
Total contributions
Interest earned
How compound interest works
Compound interest means interest is added to the balance and future interest is then calculated on both the original principal and previously earned interest.
More frequent compounding can slightly increase the final balance when the annual rate is the same.
Optional monthly contributions are added throughout the investment term and also earn interest after they are deposited.
Important
This calculator provides a mathematical estimate only. It does not account for taxes, fees, changing interest rates, inflation or investment risk.
How to use it
Enter the initial principal, annual interest rate, investment term and compounding frequency. Optionally add a monthly contribution to estimate the final balance and total interest earned.
Privacy
Calculations are performed locally in your browser. The values you enter are not submitted to Muft.
Tool behavior last checked Aug 23, 2026.