How to use this calculator
- Enter starting amount, nominal annual rate (%), monthly payment.
- Choose a display currency, then select Calculate. Results also update after a brief pause while you edit.
- Read the result with the assumptions below. Export details or save a second scenario to compare your choices.
Formula and method
Assumptions and limitations
Constant nominal rate, monthly interest and fixed end-of-month payment. Payments that do not cover interest are rejected. A maximum 1,200-month modeled horizon applies.
Worked example
A 1,050 balance at 0%, paid at 100 monthly, takes 11 payments: ten of 100 and a final payment of 50.
What the result means
Read the final payment rather than multiplying a fractional payoff time by the regular payment. The schedule reconciles the actual amounts paid.
Common questions
What if my payment does not cover interest?
The tool reports that the balance will not amortize under the stated assumptions.
How is the last payment handled?
It is capped at the remaining principal plus that month’s interest.
Methodology and transparency
Calculation specification reviewed on 2026-10-14. Mathematical implementation is tested against independent reference fixtures. This does not imply review by a licensed financial professional. Read the testing and precision policy.
Background reference: openstax.org — financial method. FinanceMath implements its own calculator.