Finance & Money
Compound Interest Calculator - Estimate Growth
Calculate compound interest growth with regular monthly contributions.
Formulas and edge cases are reviewed against authoritative references before publication. For methodology, editorial standards, or corrections, use the links below.
Frequently asked questions
What is compound interest?
Compound interest means you earn interest on both your principal and the interest already earned.
Does compounding frequency matter?
Yes. More frequent compounding slightly increases your ending balance.
Are contributions required?
No. You can set monthly contributions to zero to see growth on the initial deposit only.
Related tools
About this tool
Use this compound interest calculator to estimate how your savings or investment may grow with a fixed annual rate and optional monthly contributions. Enter an initial deposit, the annual interest rate (%), and the time horizon in years. Add a monthly contribution if you plan to invest regularly, and choose the compounding schedule (monthly, quarterly, or annually). The results show the ending balance, the sum of your contributions, and the interest earned.
Compounding applies the periodic rate (annual rate divided by periods per year) across the selected number of periods. For this estimate, the monthly contribution is converted to the selected compounding interval. Total interest is computed as ending balance minus total contributions. Values are rounded to 2 decimals and assume the rate stays constant.