Estimate payoff time, final payment, and interest savings from a recurring extra payment.
The calculator keeps the balance, rate convention, payment timing, fees, and term visible so you can reproduce the result and compare it with an actual offer or statement.
The cash-flow relationship
Place every amount at the correct time
Each month applies interest, the original scheduled payment, and the entered extra amount; the final payment is capped at the amount actually due.
Visual explanation
What changes the borrowing result
Opening balance
interestprincipal
Monthly paymentClosing balance falls over timeEach month applies interest, the original scheduled payment, and the entered extra amount; the final payment is capped at the amount actually due.
Read the result in context
Use the estimate with its contract assumptions
Adding 200 per month to a 120,000 zero-rate, 120-month loan changes the payoff from 120 months to 100 months.
Confirm how a lender applies extra payments and whether a penalty applies. The model assumes every extra amount reduces principal in the same month.
Quick guide
How to use this calculator
Enter every amount in one consistent currency.
Use the nominal annual rate and whole-number monthly timing requested by each label.
Read the result together with the stated timing convention and calculator-specific exclusions.
Calculation method
Calculation method
Each month applies interest, the original scheduled payment, and the entered extra amount; the final payment is capped at the amount actually due.
Entered monetary components are aggregated as exact fixed decimals. Amortization keeps full calculation precision and rounds only for presentation; a nonzero supported result is never displayed as zero.
Worked example
Worked example
Adding 200 per month to a 120,000 zero-rate, 120-month loan changes the payoff from 120 months to 100 months.
Each month applies interest, the original scheduled payment, and the entered extra amount; the final payment is capped at the amount actually due.
Supported inputs
Precision and limits
Visible input limits
Amounts are capped at 1e12, nominal annual rates at 1000%, schedules at 1,200 months, and fixed-decimal inputs at 12 decimal places.
Estimate, not an offer
Results model only the entered values. A lender or contract may use different payment dates, day counts, compounding, fee treatment, statement rounding, or allocation rules.
International scope
No currency, country, tax, credit-scoring system, consumer-credit law, or lender policy is assumed. Location-dependent amounts must be entered explicitly.
Calculator-specific assumptions
Confirm how a lender applies extra payments and whether a penalty applies. The model assumes every extra amount reduces principal in the same month.
