Ask ten people when refinancing is worth it and you will get the same answer: when rates drop by at least 1%. It is a tidy rule, it is widely repeated, and it is close to useless. It says nothing about your remaining term, your closing costs, or how long you plan to stay in the house — which are the three things that actually decide the outcome.
Here is what to test instead.
#Test 1: Does the break-even land inside your horizon?
This is the only test that genuinely matters. Every refinance costs money upfront and returns money over time. Break-even is the month those two cross.
If your closing costs are $6,400 and the refinance saves $310 a month, the naive break-even is 21 months. If you plan to be in the house for eight more years, that is an easy yes. If you are eyeing a job in another city next spring, it is an obvious no.
The trap is that the naive calculation only works when the new term matches the old one. Refinance a 27-year remaining balance into a fresh 30-year loan and your payment drops partly because you stretched the debt, not because the rate improved. A proper break-even calculation compares both amortisation schedules and credits the difference in outstanding balance, so a shorter term is not unfairly penalised and a longer one is not unfairly rewarded.
#Test 2: What happens to lifetime interest?
A lower monthly payment is not a saving. It is a cash flow change that may or may not be a saving.
Consider a borrower eight years into a 30-year loan at 6.85%. Refinancing into a new 30-year at 5.75% cuts the payment noticeably — and adds eight years back onto the debt. Total interest over the life of the loan can rise by tens of thousands of dollars even though every monthly statement looks better.
Compare total interest on both loans before you compare payments. If the payment falls and lifetime interest rises, you have borrowed against your future self and called it a saving.
#Test 3: Are you removing PMI?
This one is frequently overlooked and often decisive. If your equity has passed 20% through payments or appreciation, refinancing can eliminate private mortgage insurance entirely.
PMI commonly runs $120 to $300 a month on a mid-sized loan. That saving arrives regardless of what happens to your interest rate, which means a refinance at the same rate can still be worth doing. Add your current PMI figure to any calculation — leaving it out will make the refinance look far worse than it is.
#Test 4: What is the real closing cost?
Use the total from your official Loan Estimate, not the number in the advertisement. Closing costs typically run 2% to 5% of the loan amount and include origination, appraisal, title insurance, recording fees and prepaid escrow.
Watch for two things. Points are prepaid interest — buying down the rate makes sense only if you keep the loan well past the point's own break-even. Lender credits work in reverse, covering costs in exchange for a higher rate, which is what a "no-closing-cost" refinance actually is.
#Test 5: Should you roll the costs in?
Financing $6,400 of closing costs into the loan preserves cash today and costs roughly $13,500 over thirty years at 5.75%. Whether that is a good trade depends on what else your cash could do.
The general rule: pay costs in cash if you expect to keep the loan well past break-even. Finance them if the cash has a better use — clearing a credit card at 22%, for example, beats saving 5.75% every time.
#The number that overrides everything
How long you will actually stay. Homeowners consistently overestimate this. The median US tenure is well under a decade, and life events — a job, a relationship, a school district — move faster than transaction costs can be recovered.
If your honest answer is "probably four years, maybe less", a refinance needs to break even inside about two years to be worth the paperwork. Run your own numbers rather than trusting the rule of thumb; the refinance calculator gives you the exact month.
Frequently asked questions
Is the 1% rule for refinancing still valid?
No. It was a reasonable heuristic when closing costs were more uniform and most borrowers held 30-year loans to term. Today the decision depends on your remaining term, your specific closing costs, whether PMI is removed and how long you will stay. A rate drop of 0.5% can be clearly worth it for one borrower and clearly not for another.
Can I refinance more than once?
Yes, and there is no legal limit. Each refinance restarts the break-even clock and incurs a fresh set of closing costs, so serial refinancing only makes sense when rates have moved substantially since the last one. Some loans carry prepayment penalties in the first few years, so check your note.
Does refinancing hurt my credit score?
Temporarily and slightly. The hard inquiry and the new account lower the average age of your credit, typically costing a few points that recover within a year. Rate shopping within a 45-day window is treated as a single inquiry by all major scoring models, so compare lenders freely.