Tool 01 of 10

Compound Interest Calculator

ReviewedLast reviewed Oct 2026 · Educational formulas

Project how an initial deposit and regular monthly contributions grow over time with compound interest.

Inputs

Optional. Added at the end of each month.
Nominal annual rate.

Results

Enter your values and press Calculate. Results update live after the first calculation.

How it works

Interest is added to the balance at your chosen compounding frequency, so future interest is earned on past interest. We convert the nominal rate to an equivalent monthly rate, (1 + r/n)n/12 − 1, then step month by month, adding your contribution at the end of each month.

Without contributions this matches the classic formula A = P(1 + r/n)nt. Taxes, fees and changing rates are not included.

Estimates for educational purposes only. Results are approximations and not financial advice. See the disclaimer.