Refinance Break Even Calculator: When the Term Reset Moves the Answer

October 16, 2026 · Homes and property

The refinance break-even point is the number of months it takes for a lower payment to pay back the closing costs: closing costs divided by the monthly saving. On an illustrative $280,000 balance moving from 7.25% to 6.25% with $5,600 of closing costs, the payment drops by $299.85 a month and the simple break-even is 18.7 months. That is the right first number. But if the new loan restarts a 30-year clock, the saving is partly the loan being stretched out, and counting what you still owe moves the break-even to month 25 - and paid to the end, this particular refinance costs $19,085 more than keeping the old loan. Whether that matters depends on your numbers, and the rest of this page shows how to tell.

The refinance break-even formula

Monthly saving     = current payment - new payment
Break-even months  = closing costs / monthly saving

Both payments are principal and interest only. Taxes and insurance are the same whichever loan you have, so they do not change the answer. The payment on each loan is the standard level-payment formula:

Payment = balance × r / (1 - (1 + r)^-n)

where r is the annual rate divided by 12 and n is the number of monthly payments left.

Worked example: the simple answer

All figures are illustrative, not rate quotes or lender fees:

• Balance owed today: $280,000
• Current rate 7.25%, with 300 months (25 years) left
• Refinance offer: 6.25% on a new 30-year loan
• Closing costs: $5,600

The current payment is $2,023.86. The new payment is $1,724.01. The monthly saving is $299.85, so:

Break-even = $5,600 / $299.85 = 18.7 months (about 1.6 years)

That is the standard refinance break-even point, and it is a useful one. If you expect to sell or refinance again well before 18.7 months, this refinance does not get its costs back, and you can stop there.

The non-obvious part: the term reset

The simple formula compares payments. It does not look at the balance. Here the old loan has 25 years left and the new one runs 30, so 60 months (5 years) of payments are added back onto the end. A longer loan has a lower payment even at the same rate, because each payment repays less principal. Part of the $299.85 saving is the rate cut; part is simply paying off the house more slowly.

Two ways to see what that does.

1. Count the balance, not just the payments

If you sell after 4 years (48 months), you owe $261,566 on the current loan or $265,554 on the new one - $3,988 more, because the 30-year loan paid down more slowly. The fair comparison is everything you hand over by the sale: payments, plus the payoff at the sale, plus the closing costs on the refinance.

Run that month by month and the refinance first comes out ahead in month 25, not month 19. At month 19, where the simple formula says the costs are paid back, the new loan’s balance is $1,375 higher, and the refinance is still $1,278 behind.

By the 4-year sale it is ahead by $4,804, so in this example the refinance still pays if you stay that long. The honest break-even is just 6 months later than the simple one.

2. Paid to the end, it can cost more

If you keep the loan to the last payment, the totals look like this:

• Interest left on the current loan: $327,158
• Interest on the new 30-year loan: $340,643
• Plus closing costs: $5,600

A full point lower rate, a payment $299.85 lower, and yet the refinance costs $19,085 more over its life, because of those 60 extra months of payments.

Same refinance, same payoff date

The cleanest way to separate the rate cut from the stretch is to ask for a new loan that ends when the old one would have. Same balance, same rate, same closing costs:

The same-term loan saves less each month ($176.78), so its simple break-even is later: 31.7 months. But it now saves $47,435 over its life instead of costing more. And counting the balance, it comes out ahead in month 24, earlier than its own simple break-even, because the lower rate pays the balance down faster than the old loan did.

So the simple formula is not wrong in general. It can land late or early, depending on whether the new loan pays the balance down faster or slower than the old one. The term reset is what pushes it the flattering way.

It depends on how far into the old loan you are

The reset only costs extra when the years added back outweigh the rate cut. Hold the balance, rates and costs the same and change only the years left on the current loan:

With 25 years left, resetting to 30 costs $19,085 more over the life of the loan. With 27 years left it saves $12,602; with 29 years left it saves $44,966. Nothing about the refinance changed except how much of the clock it restarts. That is why “should I refinance my mortgage” has no answer without your own months left, rate, costs and plans.

A refinance break-even rule of thumb that holds up

The arithmetic above supports a short checklist rather than a single number:

1. Simple break-even first. Closing costs divided by monthly saving. If you will move or refinance again before then, stop.
2. Then the balance test. If the new term is longer than the time left on your current loan, compare payments plus the balance owed at your likely sale date. That gives the break-even month you can actually rely on.
3. Then the lifetime test, if you might keep the loan to the end. If it costs more in total, ask what a loan ending on your original payoff date would cost instead.

You can also do the reset refinance and keep paying the old amount: the extra goes to principal and the loan finishes sooner. That is a choice you have to keep making every month, so compare it on the same numbers before relying on it.

How these were calculated

Payments use the level-payment formula above on the illustrative inputs. Interest totals are the payments over the full term minus the balance. The balance-counting break-even is the first month in which payments plus the remaining balance on the current loan exceed payments plus the remaining balance plus closing costs on the new loan. It treats a dollar today and a dollar at the sale alike, with no allowance for what the closing costs could have earned elsewhere, and assumes no overpayments.

Every figure was computed twice: once by the code behind the calculator pack below, and once by an independent month-by-month loop written for this page (which finds each payment by trial rather than by formula). The two agree to the cent before anything is published. The rates, balance and closing costs are illustrative examples, not market rates or quotes. This is not financial advice; get a Loan Estimate from a lender and run your own numbers.

If you want to run the simple break-even, the term reset, the same-term version and the planned-sale test on your own loan, the spreadsheet pack below has each one as an editable sheet with the formulas visible.