Mortgage Payoff Calculator
The Mortgage Payoff Calculator shows exactly how much time and interest you save by making additional principal payments each month. Even a modest extra $100–$200 per month can eliminate years of payments and tens of thousands of dollars in interest. Enter your current loan balance, rate, remaining term, and extra payment amount to see your new payoff date and total interest savings side by side.
Applied directly to principal each month
Regular Monthly Payment
$1,995.91
Original Payoff
30 yr 1 mo
New Payoff with Extra Payment
22 yr 11 mo
Months Saved
7 yr 2 mo
Interest Saved
$116,640.00
Total Interest (No Extra Payments)
$418,526.69
How to use this calculator
- 1
Enter your current loan balance
Input the outstanding principal on your mortgage — this is the remaining balance, not the original loan amount.
- 2
Enter your interest rate
Input your current annual mortgage interest rate as a percentage (e.g. 7 for 7%).
- 3
Select remaining loan term
Choose how many years are left on your current loan. If you have a 30-year mortgage with 5 years elapsed, select 25 years.
- 4
Enter your extra monthly payment
Type the additional amount you plan to pay each month beyond your regular payment. This amount is applied entirely to principal.
- 5
Compare the results
The calculator displays your regular payment, original payoff timeline, new payoff timeline, months saved, and total interest saved.
Formula
Regular Payment: M = P[r(1+r)^n] / [(1+r)^n − 1]
Month-by-month simulation:
Interest charge = Balance × r
Principal paid = M + ExtraPayment − Interest charge
New Balance = Previous Balance − Principal paid
Repeat until Balance ≤ 0
Months Saved = Regular payoff months − Early payoff months
Interest Saved = Total interest (regular) − Total interest (extra payments)The calculator first computes your standard monthly payment using the amortization formula, then runs a month-by-month simulation applying the extra payment directly to principal each period. Because interest is calculated on a declining balance, each extra principal payment reduces future interest charges and accelerates payoff. Example: a $300,000 loan at 7% over 30 years has a regular payment of ~$1,996 and total interest of ~$418,500. Adding $200/month cuts payoff to about 25 years and saves roughly $75,000 in interest.
Worked Example
Loan Balance: $300,000 Annual Rate: 7.00% Remaining Term: 30 years Regular Payment: ~$1,996/month Total Interest: ~$418,500 With $200 Extra per Month: New Payoff: ~25 years (300 months → ~299 months saved: ~61 months) Months Saved: ~61 months (~5 years, 1 month) Interest Saved: ~$75,000 Verification: $200 × 299 months = $59,800 extra paid, but saves ~$75,000 in interest — a net benefit of ~$15,200 beyond the extra payments made.