Free Compound Interest Calculator
Model compound investment growth with contributions, fees, optional final gain tax, and inflation. Compare hypothetical rates and review a yearly schedule.
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Formula
For the basic monthly-compounding, month-end-deposit case before fees/tax: A = P(1 + i)^n + C × ((1 + i)^n − 1) ÷ i; at 0%, A = P + C × n. Extended settings simulate selected timing, contribution frequency, balance fees, and final positive-gain tax month by month. The term must equal whole months.
Worked example
With $5,000 initially, $100 deposited at each month-end, a 7% nominal annual rate compounded monthly, and 10 years, the estimate is about $27,356.79. Actual investment returns vary and are not guaranteed.
What the result means
A hypothetical projection using the selected rates, compounding, contributions, fees, and tax/inflation assumptions. Defaults use monthly nominal compounding and month-end deposits. Comparisons and user-entered yearly returns are scenarios, not forecasts or recommendations.
How to Use Compound Interest
Input Principal
Starting amount.
Set Rate
Annual return %.
Key Features & Benefits
Yearly schedule
Separate contributed amounts from modeled growth and download the schedule locally.
Frequently Asked Questions
Can I choose compounding frequency?
Yes. Choose an effective annual rate or a nominal rate compounded annually, semiannually, quarterly, monthly, or daily.
Are the returns guaranteed?
No. The rates and comparisons are assumptions you enter; results do not predict investment performance.
Key terms
- Compounding
- Interest on interest.