Extra Payments Mortgage Payoff Calculator
Extra principal ends your mortgage sooner and cuts the interest. On a $300,000 loan at 4.5% with 25 years left, an extra $250 a month ends it 5 years 3 months sooner and saves $47,596 of interest.
Enter your own loan in the calculator, then read the tables to see how the size and the timing of the extra change the result.
Extra payment payoff calculator
Payoff with no extra: 25 years, $200,249 of interest.
Payoff with the extra: 19 years 9 months, $152,654 of interest.
You save $47,596 of interest and finish 5 years 3 months sooner.
Extra every month
The loan is $300,000 at 4.5% with 25 years left, a payment of $1,667.50. With no extra it ends in 25 years and costs $200,249 in interest.
| Extra a month | Paid off in | Sooner by | Interest paid | Interest saved |
|---|---|---|---|---|
| $100 | 22 years 7 months | 2 years 5 months | $177,863 | $22,386 |
| $250 | 19 years 9 months | 5 years 3 months | $152,654 | $47,596 |
| $500 | 16 years 4 months | 8 years 8 months | $123,863 | $76,387 |
| $1,000 | 12 years 3 months | 12 years 9 months | $90,355 | $109,894 |
One $10,000 payment: early or late
The same $10,000 saves less the later it is paid, because it removes interest for fewer months.
| Paid after | Paid off in | Sooner by | Interest saved |
|---|---|---|---|
| 1 year | 23 years 7 months | 1 year 5 months | $18,510 |
| 5 years | 23 years 10 months | 1 year 2 months | $13,945 |
| 15 years | 24 years 3 months | 0 years 9 months | $5,428 |
How the calculator works
- The required payment comes from the standard loan formula for your balance, rate and years left.
- Each month, interest = balance x rate / 12. The payment plus the extra, minus that interest, comes off the balance.
- The count stops when the balance reaches zero. Interest is the sum of every month's interest.
It assumes a fixed rate and that the extra lands on principal on the due date. For the payment formula see how to calculate a recast payment, and for a lump sum that lowers the payment instead, recast vs extra principal payment.
Check before you send extra
The CFPB says a prepayment penalty is a fee that some lenders charge if you pay off all or part of your mortgage early.
Look for it in your closing papers or ask your servicer. Also ask how extra money is applied. For a worked version of the same math on a loan with a different rate, see the mortgage payoff calculator walk-through.
Frequently asked questions
How much does an extra $100 a month save?
On the example loan it ends the mortgage 2 years 5 months sooner and saves $22,386 of interest. The saving grows faster than the extra: $1,000 a month saves $109,894, more than ten times as much for ten times the extra.
Is one big payment better than small monthly extras?
Per dollar they save the same interest if they land on the same day, because interest is charged on the balance. What differs is when the money arrives: the earlier a dollar reaches principal, the more interest it removes.
Does an extra payment change my monthly payment?
No. The required payment stays the same and the loan ends sooner. A recast is the way to lower the payment after a large payment.
Should the extra go to principal?
Yes. Tell your servicer to apply it to principal. Extra money applied to the next payment instead does not lower the balance, so it saves no interest.
How do I get the payoff date in a spreadsheet?
Use NPER(rate/12, -(payment + extra), balance). It returns the number of months. Divide by 12 for years.
Sources
Every figure on this page comes from the pages below. Checked 2026-11-05. Rules change, so confirm with your own servicer.
- CFPB: What is a prepayment penalty? (the definition of a prepayment penalty)
More recast guides
- Free Mortgage Recast Calculator - enter your own loan and see the new payment.
- Recast vs Refinance Calculator - Compare both options on the same loan, with a break-even point.
- Recast Fees and Rules by Lender - Fees, minimums and loan limits published by four large lenders.
- How to Calculate a Recast Payment - The formula, a step-by-step example and the numbers to check.
- How Much Will a Recast Lower My Payment? - The lump sum divided by balance shortcut, with lookup tables.
- Recast vs Extra Principal Payment - The same lump sum two ways: payment, payoff date and interest.
- Recast Amortization Schedule - Balance and interest by year, before and after a recast.
- Chase Mortgage Recast Calculator - No stated minimum, what the lender page says and what a lump sum does.
- Wells Fargo Mortgage Recast Calculator - The jumbo loan recast option, the $10,000 starting point and the rate used.
- Bank of America Mortgage Recast Calculator - Eligibility, timing and an estimate the lender will not give you.
- Best Mortgage Recast Calculator: What to Check - Seven checks and a test loan with the right answer.
- Mortgage Recast Calculator in Excel or Google Sheets - Cell-by-cell layout with PMT, interest saved and a fee break-even.
- How Much Does a Mortgage Recast Cost? - What lenders publish about the fee, and months to pay it back.
- Mortgage Recast Savings Calculator - Monthly saving, interest saved and the net after a fee, by lump sum.
- Home Loan Recast Calculator - The three numbers to enter and three worked loans.
- What Is a Mortgage Recast? - What changes, what stays the same, with a worked example.
- Dave Ramsey Mortgage Payoff Calculator Explained - What the calculator asks for, a loan you can check and a calculator of your own.
- Amortization Schedule for a Balloon Mortgage - Balance by year and the balloon due at the end of a 5, 7 or 10-year term.