Mortgage Payoff Calculator
See how much time and interest you save by making extra payments toward your mortgage principal.
Inputs
Applied directly to principal every month.
Interest Saved
$79,680
Years Saved
5.8years
Months Saved
70months
Current Monthly Payment
$1,835.55
New Monthly Payment
$2,035.55
Original Total Interest
$314,719
New Total Interest
$235,040
New Payoff In
21y 2m
Payoff timeline with extra payments applied every month.
Step by step
Scheduled monthly payment (P&I)
= $1,835.55
New monthly payment with extra
$1,835.55 + $200.00
= $2,035.55
Original payoff timeline
= 324 months
Payoff with extra payments
= 254 months (21y 2m)
Time saved
324 − 254
= 70 months (5.8 years)
Interest saved
$314,719 − $235,040
= $79,680
How it works
Every extra dollar you pay toward principal reduces the balance on which future interest accrues. This compounding benefit means even a small regular extra payment shortens your term and saves a multiple of the payment in interest over time. The calculator runs the full amortization schedule both ways and differences the results.
Formulas
Scheduled payment
M = P × r(1+r)ⁿ / ((1+r)ⁿ − 1)
- P
- Remaining loan balance
- r
- Monthly interest rate (annual rate ÷ 12)
- n
- Remaining number of months
- M
- Scheduled monthly payment
Interest saved
Interest saved = Total interest (no extra) − Total interest (with extra)
Guides that use this calculator
Results are estimates assuming a fixed interest rate and consistent extra payments. Actual savings depend on your lender's application timing and any prepayment restrictions.
Frequently Asked Questions
Does the extra payment go entirely to principal?
Yes — once the month's interest is satisfied, any additional amount reduces the outstanding principal balance directly. Your lender applies the standard payment first (interest then principal) and any extra to principal only.
When should I make the extra payment?
Extra payments save the most when made early in the loan when the balance is highest. Even a single extra payment in the first year can save thousands in interest. Consistent monthly extra payments produce the largest benefit.
Is there a prepayment penalty I should check?
Some mortgages, particularly older ones, include a prepayment penalty clause if you pay off more than a set amount early. Check your loan documents or ask your servicer before making large extra payments.
How does this compare with refinancing?
Refinancing typically lowers your rate and restarts your term, while extra payments keep your rate but shorten the term. Use the Refinance Calculator to compare both strategies side by side.