How to use this calculator
- Enter your own values in the labeled fields. Check the units and assumptions before comparing results. Only the fields needed for your selected calculation mode are shown.
- Your answer updates automatically. Review the calculation steps to see exactly how it was calculated.
- Copy, share, save, or download your result. Saved inputs stay on this device.
How the calculation works
Compounding means that interest becomes part of the balance that earns future interest. This model converts your selected compounding frequency into an equivalent monthly growth factor, then applies monthly contributions at the selected time. Keep nominal rate and effective annual yield distinct. Actual deposit products can use daily accrual, different deposit timing, and tax withholding.
A worked example
Start with $10,000, add $200 at each month-end, and assume 6% nominal interest compounded monthly. In 10 years, contributions total $34,000; the projected balance is about $50,969.84.
Reading your result
Use the main result together with its units and supporting figures. Display values are rounded; calculations keep their underlying precision. A change in inputs or assumptions can change the answer. Compare the step-by-step working with your intended use before relying on an estimate.
Frequently asked questions
Can I add money every month?
Yes. Enter a monthly contribution and choose whether it is added at the beginning or end of each month.
Are returns guaranteed?
No. A constant rate is a planning assumption. Taxes, fees, and inflation are excluded.
Sources & methodology
This calculator uses the mathematical identity and assumptions stated above. No current rates, prices, or external data are loaded. Conversion tools use international unit definitions.
Formula review: October 24, 2026. Read our methodology.