How to use this calculator
- Enter loan principal, nominal annual rate (%), monthly periods.
- 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
The model has a fixed rate and an end-of-term balloon. It does not model a later amortizing phase, fees or refinancing availability.
Worked example
Principal of 10,000 at 6% for 24 months has monthly interest of 50, total interest of 1,200 and a 10,000 principal balloon.
What the result means
Model an interest-only period with full principal redemption at its end.
Common questions
How is the calculation performed?
Monthly interest = principal × nominal annual rate / 12. Principal is repaid as a balloon with the final interest payment.
What does the model leave out?
The model has a fixed rate and an end-of-term balloon. It does not model a later amortizing phase, fees or refinancing availability.
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.