What break-even actually measures
A refinance trades a one-time cost for a stream of smaller monthly payments. The break-even point is the moment the accumulated payment savings finally equal what you spent to get them. Before that month you are behind; after it, every payment is money you would not otherwise have kept.
The arithmetic is deliberately simple: divide total closing costs by the monthly payment reduction. If you pay $6,500 to close and your payment drops $240, you need roughly 28 payments — a little over two years — before the refinance has paid for itself. Anything that shortens your expected time in the home, such as a likely job relocation or a planned upsize, should be compared directly against that number.
Why the payment drop is not the whole story
Lowering your rate while resetting the clock to a fresh 30-year term almost always reduces the monthly payment, because you are stretching the remaining balance over more months. That is a genuine cash-flow win, but it can raise the total interest you pay across the life of the loan. This calculator reports both figures side by side for exactly that reason: the Break-even point answers "when does this stop costing me money each month," while Lifetime interest difference answers "does this cost me more in total."
If lifetime interest goes up but break-even is short, the refinance is a liquidity decision, not a savings decision. That can still be the right call — freeing $300 a month matters more than abstract interest totals if you are carrying credit card balances. Just make the trade knowingly.
Rolling costs into the loan
Choosing to finance closing costs sets the upfront cash outlay to zero, which mathematically makes break-even immediate. That is misleading if you read it carelessly. You have not avoided the cost; you have borrowed it at the new mortgage rate and will repay it with interest over the term. Compare the two modes: pay cash and watch the break-even month, or roll it in and watch the lifetime interest figure grow. The honest comparison is total dollars over the horizon you actually expect to hold the loan.
How to read the chart
The curve starts below zero by the amount of your closing costs and climbs at the rate of your monthly savings. Where it crosses the horizontal axis is your break-even month. A steep curve means a strong refinance; a shallow curve that crosses late means the deal is marginal and sensitive to how long you stay.
When to walk away
Break-even beyond roughly five years deserves scepticism, because the median homeowner moves or refinances again well before then. Also check whether the quoted rate includes discount points — paying points is itself a mini-refinance decision with its own break-even, and it inflates the closing cost figure you enter above.