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Compound Interest Calculator
Calculate the growth of an initial balance and regular monthly contributions at an assumed annual return.
- Future balance
- 47,161.58
- Total contributions
- 34,000
- Investment growth
- 13,161.58
How the calculation works
FV = P(1+r)^n + C((1+r)^n−1)/r; r = (1+annual return)^(1/12)−1. At zero interest FV = P + Cn.
Inputs
- Starting balance
- End-of-month contribution
- Effective annual return, %
- Term, months
Calculation details
The constant return is supplied by the user. This is a scenario, not a forecast; taxes, fees, and inflation are not automatically deducted.
Contributions occur at each month end. The effective annual return is converted to an equivalent monthly rate using the twelfth root.
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Updated: 2026-10-02