Summary
Use this when you want to see how principal, contribution size, compounding frequency, and time combine — and how much of the future value is interest versus money you put in.
Calculation details
Interest is credited at the selected frequency. Each recurring contribution is added at the end of its period and therefore begins earning interest in the following period. Results assume a constant rate; they are not a market forecast.
Formula
FV = P(1 + r)^n + C[(1 + r)^n − 1] ÷ r. At 0%, FV = P + Cn.
Worked example
$10,000 compounded monthly
$10,000 at 5% for 10 years with $100 deposited at each month end grows to approximately $31,998.32.
How it works
Choose a compounding interval, enter the contribution that matches that interval, and compare total contributions with accumulated interest. Shorter compounding intervals usually raise future value slightly under the same stated annual rate.
Frequently asked questions
What does this compound-interest calculation estimate include?
It assumes a constant rate and ordinary end-of-period contributions.
When is this compound-interest calculation most useful?
When projecting growth under a fixed rate and contribution schedule before comparing account options.
Are displayed values rounded?
The formula keeps full numeric precision. Values are rounded only when formatted for display.
Can actual results differ?
Yes. Variable rates, fees, taxes, contribution timing, and compounding conventions can change the outcome.