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Financial
Compound Interest Calculator
Project how investments grow over time with compound interest and recurring monthly contributions.
How the Compound Interest Calculator Works
This calculator estimates the future value of an investment over time, taking compound interest and regular monthly contributions into account. Compounding means you earn interest on your principal plus the interest you have already accumulated.
Formula Used
FV = P × (1 + r)ⁿ + C × [((1 + r)ⁿ − 1) ÷ r]
- FV
- — Future Value of the investment
- P
- — Principal (initial investment amount)
- r
- — interest rate per compounding period (annual rate ÷ periods per year)
- n
- — total number of compounding periods (years × periods per year)
- C
- — regular contribution amount made at each compounding interval
Example Calculation
If you invest $10,000 at 5% annual interest compounded monthly (r = 0.05 / 12 = 0.004167) for 10 years (n = 120) with a $100 monthly contribution: Future value = $31,998.32. Total contributions were $22,000, and interest earned was $9,998.32.