Compound Interest Calculator
Project compound growth with whole-month durations and optional end-of-month contributions.
Fixed-rate growth estimate
The annual rate is treated as a nominal rate with your selected compounding frequency. Contributions are added at the end of every month. Enter every amount in one currency; results use those same entered currency units and no currency conversion is performed.
May be zero when the monthly contribution is greater than zero.
Use a whole number of months, up to 100 years (1,200 months); 0.5 years is 6 months.
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Continue with related pages to compare results and improve decision making.
How This Compound Interest Calculator Works
This compound interest calculator projects a hypothetical future value from an initial amount, nominal annual return, compounding frequency, whole-month duration, and optional end-of-month contributions. It does not model fees, tax, inflation, or variable returns.
Formula and Calculation
The core formula used by this compound interest calculator is: Principal growth follows A = P(1 + r/n)^(nt). Optional contributions are deposited at the end of each month and grow using the monthly rate equivalent to the selected compounding frequency.
The equation applies returns to principal and accumulated gains. The calculator converts the selected nominal compounding convention to an equivalent monthly factor so it can model whole-month durations and monthly contributions consistently.
An initial 10,000 earning a nominal 8% compounded monthly for one year, with 500 added at the end of each month, projects to about 17,054.96: 16,000 contributed and about 1,054.96 of growth.
How to Use This Calculator
- Enter initial investment amount.
- Set expected annual return and compounding period.
- Add an optional contribution made at the end of every month.
- Review projected ending value, total contributions, and projected growth.
Why Use This Compound Interest Calculator?
- Visualize long-term growth before investing.
- Compare contribution strategies and expected returns.
- Set realistic financial goals with timeline clarity.
- Understand the value of starting early.
Related Tools and Guides
- Try the Loan Calculator for a related calculation.
- Try the Mortgage Calculator for a related calculation.
- Read the Compound Interest Calculator Guide for examples and assumptions.
- Browse the Finance Calculators page for more tools.