How to use this calculator
- Choose what you know. Enter your current balance and the time left from your latest statement, or switch to original loan and enter the original amount, term and first payment date; the calculator works out today’s balance.
- Interest rate and next payment date. The date sets the calendar month for your new payoff date.
- Choose a goal.
- Pay extra: add an extra amount every month, a yearly extra (paid with every 12th payment), a one-time lump sum with your next payment, or switch to a biweekly schedule. Combine them however you like.
- Pick a payoff date: enter how many years you want the loan to last, and the calculator solves for the extra monthly payment you need.
You’ll see your new payoff date, interest saved and time saved, a chart comparing your balance with and without extra payments, and a year-by-year schedule you can download.
How extra payments shorten a mortgage
Each monthly payment first covers the interest for that month (balance × rate ÷ 12) and the rest reduces the principal. An extra payment skips the interest step entirely: every dollar cuts the balance, so every later month charges interest on a smaller number. That’s why the savings are larger than the extra money you put in.
The number of payments it takes to clear a balance B with a monthly payment A at monthly rate r is:
Adding an extra amount to A makes n smaller. The calculator runs the loan month by month instead, rounding interest to the cent the way servicers do, so it can handle yearly extras and lump sums too.
To hit a target date, it works the other way: the payment that pays B off in the target number of months, minus your current payment, is the extra you need.
Worked example
You owe $280,000 at 6.5% with 25 years left. Your principal and interest payment is $1,890.58, and you’re on track to pay $287,174 more in interest.
Add $200 a month and:
- The loan is paid off in 20 years instead of 25.
- You pay $66,894 less interest.
- You put in $47,800 of extra payments in total, so each extra dollar saves about $1.40 of interest.
How much each extra amount saves
Same $280,000 balance at 6.5% with 25 years left:
| Extra each month | Paid off in | Time saved | Interest saved |
|---|---|---|---|
| $100 | 22 years 2 months | 2 years 10 months | $38,337 |
| $200 | 20 years | 5 years | $66,894 |
| $300 | 18 years 3 months | 6 years 9 months | $89,151 |
| $500 | 15 years 7 months | 9 years 5 months | $121,848 |
| $1,000 | 11 years 6 months | 13 years 6 months | $169,176 |
Other ways to prepay, on the same loan:
| Strategy | Time saved | Interest saved |
|---|---|---|
| Biweekly payments (13 a year) | 4 years 2 months | $55,695 |
| $2,400 once a year | 4 years 11 months | $63,998 |
| $10,000 lump sum now | 2 years | $37,108 |
Paying off by a target date
Say you want to be mortgage-free in 15 years instead of 25. You’d need to pay $548.53 extra a month, $2,439.11 in total, and you’d save $128,137 of interest. A 10-year target takes $1,288.77 extra a month; a 20-year target takes $197.03.
If you want a shorter term and a lower rate, a 15-year refinance might get you there with less extra cash. Compare both with the refinance calculator.
About biweekly payments
A biweekly plan has you pay half your monthly payment every two weeks. There are 52 weeks in a year, so that’s 26 half-payments, or 13 full payments instead of 12. The calculator models this as one-twelfth of your payment added each month, which has the same effect.
Some servicers and third-party companies charge setup or per-payment fees for biweekly programs, and some hold your half-payments until a full payment builds up. You can get the same savings for free by adding one-twelfth of your payment as extra principal each month.
Should you pay off your mortgage early?
Prepaying a mortgage earns a guaranteed return equal to your interest rate. Before you do it, it usually makes sense to:
- Pay off higher-rate debt first. Credit cards and personal loans almost always cost more than a mortgage. See the debt payoff calculator.
- Keep an emergency fund. Money you prepay is locked in your house; getting it back means selling, refinancing or borrowing against your equity with a home equity loan.
- Capture any employer 401(k) match. A match is an immediate return that prepaying can’t beat.
- Compare with investing. If your mortgage rate is low, long-term investments may earn more, though not with a guarantee. The investment calculator can help you compare.
- Check for a prepayment penalty. Under Regulation Z, a penalty is allowed only on certain fixed-rate qualified mortgages, never after the first three years, and capped at 2% of the amount prepaid in the first two years and 1% in the third.
Assumptions and limitations
- Fixed-rate loan. Interest is charged monthly on the balance at rate ÷ 12, rounded to the cent.
- Only principal and interest are modeled. Escrow for taxes and insurance continues until the loan is paid off, and doesn’t change the payoff date.
- In current balance mode, the calculator recomputes your payment from the balance, rate and time left. If your actual payment differs slightly, use original loan mode or the amortization calculator.
- For adjustable-rate loans, results hold only until the rate changes.
Sources
These figures are estimates. Ask your servicer for an official payoff quote before making a final payment.
Frequently asked questions
How much faster will I pay off my mortgage with $200 extra a month?
On a $280,000 balance at 6.5% with 25 years left, an extra $200 a month pays the loan off in 20 years, five years early, and saves $66,894 in interest. The earlier in the loan you start, the bigger the effect, because more of each payment is interest at the beginning.
Do biweekly mortgage payments really help?
Yes, because 26 half-payments a year add up to 13 full payments instead of 12. On the example loan, that's like paying $157.55 extra a month, which finishes the loan 4 years and 2 months early and saves $55,695. You can get the same result by adding one-twelfth of your payment to each monthly payment, without signing up for a biweekly program.
Is it better to pay extra monthly or make one lump sum a year?
Paying monthly saves slightly more, because each dollar starts reducing interest sooner. In the example, $200 a month saves $66,894, while $2,400 once a year saves $63,998. The difference is small, so choose whatever fits your cash flow.
How do I make sure extra payments go to principal?
Tell your servicer the extra amount is a principal-only payment, either with a checkbox online or a note with your check. Then check your next statement to confirm the principal balance dropped by the extra amount, not that the payment was held or applied to next month's bill.
Will paying extra lower my monthly payment?
No. Your required payment stays the same; the loan just ends sooner. If you want a lower payment after a large lump sum, ask your servicer about a recast, which re-amortizes the smaller balance over the remaining term for a fee.
Is there a penalty for paying off a mortgage early?
Most mortgages don't have one. Under federal rules, a prepayment penalty is only allowed on certain fixed-rate qualified mortgages that aren't higher-priced, can't apply after the first three years, and is capped at 2% of the amount prepaid in years one and two and 1% in year three. Your Closing Disclosure states whether your loan has one.
Updated November 2026. Results are estimates for educational purposes and depend on the inputs you provide.