A mortgage calculator with extra payments: add a monthly extra, a yearly extra or a lump sum and see your early payoff date and the interest you save.
Estimates for planning, not financial, tax or legal advice. Figures use US rules unless the page says otherwise.
What it does
Every extra dollar you pay goes to principal, so the next month's interest is smaller and more of each regular payment goes to the balance. This early mortgage payoff calculator runs your loan twice, with and without the extras, and shows the new payoff date, the months saved and the interest saved.
How it's calculated
Regular payment M = B × i ÷ (1 − (1 + i)−n)
Each month: interest = balance × i; balance = balance + interest − (M + extras)
B is today's balance, i is the rate ÷ 12 and n the months left. The yearly extra is paid with every 12th payment. The schedule runs until the balance reaches zero.
Worked example
| $300,000 at 6.5%, 30 years left ($1,896.20 a month) | Paid off in | Interest saved |
|---|
| No extra | 30 years | — |
| $200 extra each month | 23 years 1 month | $103,449 |
| $5,000 extra once a year | 19 years | $158,003 |
| $20,000 lump sum in month 12 | 25 years 2 months | $91,623 |
How to pay off your house quickly
- Add a set amount to every payment. Even $100 a month cuts years off a 30-year loan.
- Put windfalls like a bonus or tax refund toward principal once a year.
- Switch to biweekly payments, which adds up to one extra monthly payment a year.
- Refinance to a shorter term if rates allow. Compare with the refinance calculator.
Limitations
- Tell your servicer the extra is for principal, or it may be held for the next payment.
- Some loans have a prepayment penalty, usually in the first three or five years. Smaller extra payments usually don't trigger it, but check with your lender.
- Escrow for taxes and insurance isn't included and doesn't change.
- Money paid into the house isn't easy to get back out. Keep an emergency fund first.
Sources
How we checked this
Before every update, this calculator is run in a real browser with these known answers, and it must match all of them:
- $300,000 at 6.5%, 30 years, $200 extra: 23 years 1 month ✓
- Same: $103,448.79 interest saved ✓
- $5,000 once a year: 132 months saved ✓
- $20,000 lump sum in month 12: $91,623.42 saved ✓
- Extra bigger than the loan: paid off in 1 month ✓
Last checked October 26, 2026. Spotted something wrong? The math is done in your browser with the formula shown on this page, so you can check any result by hand.
Questions people ask
How do I figure my mortgage payoff with extra payments?
Enter your balance, rate and years left, then the extra amount. The calculator runs the loan month by month and shows when it ends and how much interest you save.
How can I pay off my mortgage faster?
Pay more toward principal: a fixed extra every month, a yearly lump sum, or biweekly payments. $200 extra a month on $300,000 at 6.5% pays it off almost 7 years early.
How do I pay off my home loan sooner without refinancing?
Make extra principal payments directly to your servicer. Check there's no prepayment penalty and ask that the extra go to principal.
What happens if I pay one extra mortgage payment a year?
On $300,000 at 6.5% for 30 years, one extra $1,896.20 payment a year pays the loan off in about 24 years 4 months instead of 30. Enter $1896.20 in Extra once a year to try it.
Is it better to pay extra monthly or in a lump sum?
The earlier money goes in, the more interest it saves. Spread evenly, monthly extras and a yearly lump sum of the same total come out close, with monthly a little ahead.