How to use the mortgage payoff calculator
- Choose whether you know the time left on your loan or your monthly payment.
- Enter your current loan balance from your latest statement.
- Enter the interest rate on the loan.
- Enter the time left in years and months, or your monthly principal and interest payment (leave out the escrow part for taxes and insurance).
- Add an extra payment each month, a one-time lump sum, or tick biweekly payments. You can combine all three.
- Read the interest saved, your new payoff date, and the table of balances year by year.
How the payoff is calculated
If you enter the time left, the calculator first works out the payment that clears the balance exactly on schedule. It then runs the loan forward twice, month by month: once with that payment, and once with your plan (the payment plus any extra, starting from the balance after the lump sum). Every extra dollar goes straight to principal, so each later month carries a little less interest. That compounding effect is why small extras save so much.
Biweekly payments mean 26 half-payments a year, which equals 13 monthly payments instead of 12. The calculator adds one-twelfth of your payment to each month, the same total each year. Our guide to biweekly mortgage payments shows why this shortcut matches a true biweekly plan so closely.
Worked example
The defaults are a $250,000 balance at 6.5% with 25 years left, plus $200 extra a month:
- Monthly rate: i = 0.065 ÷ 12 = 0.0054167, and n = 300 months
- Payment: 250,000 × 0.0054167 ÷ (1 − 1.0054167^−300) = $1,688.02
- First month: interest is 250,000 × 0.0054167 = $1,354.17, so only $333.85 of the regular payment reduces the balance. The extra $200 raises that by 60%.
- Current schedule: 300 payments and $256,405.37 of interest
- With $200 extra ($1,888.02 a month): 234 payments (19 years 6 months) and $191,477.49 of interest
- Interest saved: $256,405.37 − $191,477.49 = $64,927.88, and the loan ends 5 years 6 months sooner
Tick biweekly as well and you pay $844.01 every two weeks plus the $200. The loan then ends in 17 years and saves $92,881.22.
Comparing payoff strategies
Here is the same $250,000 loan at 6.5% with 25 years left:
| Strategy | Paid off in | Interest saved |
|---|---|---|
| $100 extra a month | 21 years 11 months | $37,671.20 |
| $200 extra a month | 19 years 6 months | $64,927.88 |
| $500 extra a month | 14 years 11 months | $115,668.35 |
| $20,000 lump sum now | 20 years 8 months | $67,815.99 |
| Biweekly payments | 20 years 10 months | $49,727.73 |
| Biweekly plus $200 a month | 17 years | $92,881.22 |
The $20,000 lump sum and $200 a month save about the same, but the lump sum is all paid up front. The monthly $200 adds up to $46,800 over the 19.5 years. Money paid earlier saves more interest per dollar, because it stops interest from building on that part of the balance for longer.
Before you pay extra
Check that your lender has no prepayment penalty (see prepayment penalties), and ask for extra money to go to principal, not next month's payment. Build an emergency fund and clear high-interest debt such as credit cards first, since those cost more than a mortgage. If your rate is low, compare paying it down with investing; our guide on whether to pay off the mortgage or invest walks through that choice. If rates have dropped, the refinance calculator shows whether a new loan beats paying extra.
Frequently asked questions
How much faster will $100 extra a month pay off my mortgage?
On a $250,000 balance at 6.5% with 25 years left, $100 a month ends the loan 3 years 1 month early and saves $37,671.20 in interest. The earlier in the loan you start, the bigger the saving, because more of each payment is interest at the start.
Is a lump sum better than extra monthly payments?
Dollar for dollar, yes: money paid sooner stops interest building for longer. In practice it depends on what you have. A lump sum works if you get a bonus, an inheritance or a tax refund. Steady monthly extras suit a regular budget and add up to similar savings over time.
Do biweekly payments really save money?
Yes, because 26 half-payments add up to one extra monthly payment each year. On the example loan that alone saves $49,727.73 and ends the loan 4 years 2 months early. Avoid paid biweekly programs with setup fees; adding one-twelfth of your payment each month does the same thing for free.
Will paying extra lower my monthly payment?
No. Your required payment stays the same and the loan simply ends sooner. Some lenders will recast the loan after a large lump sum, recalculating a lower payment over the remaining term, usually for a small fee.
Does the calculator include taxes and insurance?
No. It covers principal and interest only, because escrow for property tax and insurance doesn't change when you pay extra. Those costs continue until the home is sold, even after the mortgage is paid off.
Related calculators
- Mortgage Calculator — Your full monthly housing cost, including property tax, insurance, PMI and HOA fees.
- Refinance Calculator — Whether refinancing pays off: new payment, monthly savings, break-even month and lifetime interest.
- Mortgage Amortization Calculator — A month-by-month mortgage schedule with dates, PMI until 78% LTV, taxes and insurance, extra payments and a yearly summary.
- Amortization Calculator — Loan amortization schedule by year, with the payoff date and what an extra monthly payment saves.
Results are estimates for educational purposes and are not financial, tax or legal advice. See our disclaimer.