Refinancing costs money up front to save money monthly. The break-even point is when the monthly savings have repaid the upfront costs. After that point you are ahead; before it, you are behind. The simple division is easy, but it is only half the decision.
The break-even formula
Break-even months = closing costs / monthly savings. Example: closing costs of $6,000 and monthly savings of $200 give 6,000 / 200 = 30 months. If you sell or refinance again before month 30, the refinance lost money. If you stay past month 30, every further month is pure gain at $200 a month.
Monthly savings = old monthly payment – new monthly payment, counting principal and interest only. Do not count tax or insurance changes unless they genuinely change, since escrow changes are not savings.
Lifetime interest: the second test
Break-even alone can mislead. A refinance that lowers the payment by stretching the term can pass the break-even test while costing more total interest. Example: refinancing a loan with 15 years left into a new 30-year loan cuts the monthly payment a lot, but adds 15 years of interest payments. Always compare total interest over the remaining life of the old loan versus the new loan.
Work it out: old loan, 15 years left at the current payment, versus new loan over its full term. If the new loan’s total interest exceeds the old loan’s remaining interest by more than the monthly savings justify, the refinance is a bad deal even with a short break-even.
The restart-the-clock trap
Restarting a 30-year term when you have already paid 10 years is the classic trap. Your payment falls, your break-even looks short, but you have added a decade of payments. The fix is simple: ask the lender for a term matching your remaining years, or keep paying the old monthly amount on the new loan. Paying the old amount on a lower-rate loan shortens the term and multiplies the interest saved.
Example: your old payment was $1,800 and the new one is $1,600. Keep paying $1,800. The extra $200 goes straight to principal every month, cutting years off the loan and thousands off total interest.
When refinancing makes sense
Refinance when the break-even is well inside your expected stay, the lifetime interest comparison is favourable, and you are not restarting the clock without a plan. Also consider the no-cost refinance option, where the lender covers closing costs in exchange for a slightly higher rate: the break-even is immediate, but the rate is worse, so compare total cost over your expected stay rather than celebrating zero upfront cost.
Cash-out refinancing
Cash-out refinancing replaces your loan with a larger one and gives you the difference in cash. It can fund renovations or consolidate debt, but it raises your balance and usually your payment, which changes the break-even maths entirely: there may be no monthly saving at all.
Judge a cash-out refinance by what the cash does, not by the payment. If the cash funds a renovation that raises the property value by more than the extra borrowing cost, it can pay. If it funds consumption, you have converted home equity into spending and extended your debt. The break-even formula still applies to the rate-saving part, but the borrowed cash itself is new debt, not a saving.
Try it faster with the tool
You can follow every step above by hand, but the free Refinance Break-Even Calculator — Months to Recover Closing Costs and Lifetime Interest Saved does the arithmetic for you. Enter your numbers and it gives the answer right away, so you can check your hand calculation or skip straight to the result.
Quick tips
- Break-even months = closing costs / monthly savings.
- Also compare lifetime interest, not just the monthly payment.
- Never restart the clock without a plan to overpay.