Calculateur de Refinancement
Votre mois de rentabilité et le coût total, pas seulement la mensualité plus basse
Break-even point and lifetime cost, not just the monthly saving
Dernière mise à jour: septembre 7, 2026
The Only Two Numbers That Decide a Refinance
Every refinance pitch leads with the monthly saving, because it is the most flattering number available. It is also the least useful one on its own. Two other figures decide whether a refinance is actually a good deal, and lenders rarely put either on the front page.
1. The break-even month
Closing costs divided by the monthly saving. Pay $6,000 to save $250 a month and you break even at month 24. Sell or refinance again before then and the deal lost you money, however good the rate looked.
2. The lifetime interest difference
A lower rate on a longer term routinely costs more in total. Refinancing eight years into a 30-year loan into a fresh 30-year loan means paying interest for eight extra years.
The calculator above shows both alongside the monthly saving, and tells you plainly when they disagree with each other.
Why a Lower Rate Can Cost You More
This is the single most misunderstood thing about refinancing, so it is worth walking through concretely.
Say you borrowed $350,000 at 7.25% on a 30-year mortgage. Eight years in, your balance is about $315,000 and you have 22 years left. Rates fall to 5.75% and refinancing looks obvious.
Refinance into a new 30-year loan: the payment drops meaningfully, which feels like a clear win. But you have just stretched 22 remaining years back out to 30. You will pay interest for eight years longer than you were going to.
Refinance at the same rate but keep 22 years: the payment drops far less — possibly barely at all — but the total interest falls sharply, because you are paying the lower rate without extending the term.
Both are legitimate choices. If your monthly cash flow is tight, the longer term is the point and the extra interest is the price you knowingly pay for breathing room. If you are refinancing purely to save money, the longer term can quietly cancel out the entire benefit of the lower rate.
The calculator shows this comparison automatically whenever your new term is longer than what you have left. Most refinance calculators do not, which is why so many people are surprised years later.
What Refinancing Actually Costs
Closing costs on a refinance typically run 2% to 5% of the loan amount. On a $300,000 refinance that is roughly $6,000 to $15,000. The main components:
- Lender origination fee — often 0.5% to 1% of the loan
- Appraisal — $400 to $800, sometimes waived
- Title search and title insurance — frequently the largest single line
- Recording and government fees — vary by county
- Prepaid escrow — not truly a cost, since it is your own money for future tax and insurance, but it is cash you need at closing
The "no-closing-cost" refinance
There is no such thing as free. The lender either folds the costs into your balance, or charges a higher rate to recover them over time. Both are legitimate — rolling costs in is genuinely useful if you lack cash at closing — but compare the total cost, not the headline rate. In the calculator, tick "roll closing costs into the loan" to model the first version, or simply enter a higher new rate to model the second.
When Refinancing Usually Makes Sense
You will comfortably pass break-even
The test is not "will I break even" but "will I break even well before I move". If break-even lands at 30 months and you expect to move in three years, the margin is too thin to be worth the paperwork and risk.
You are shortening the term, not extending it
Going from a 30-year to a 15-year at a lower rate is usually the strongest version of a refinance: the payment may rise, but total interest falls dramatically. This is the case where the lifetime figure and the monthly figure point in opposite directions and the lifetime one is right.
You can drop PMI
If your home has appreciated past 20% equity, refinancing can remove private mortgage insurance entirely. On a typical loan that is $100–$300 a month that vanishes — often worth more than the rate change. This calculator does not model PMI, so check that separately and add it to the saving.
You are leaving an adjustable-rate mortgage
Moving from an ARM to a fixed rate can be worth doing even at a similar rate, because you are buying certainty rather than savings. The calculator compares the numbers; it cannot price the risk you are removing.
When It Usually Does Not
You are moving soon. Anything under about three years and closing costs rarely get recovered.
You are deep into the loan. Amortisation is front-loaded: by year 22 of a 30-year mortgage most of your payment is already principal, so there is little interest left for a lower rate to save. Refinancing at that point mostly resets you back into the interest-heavy years.
The rate drop is small on a small balance. A quarter-point on $80,000 is a rounding error against $5,000 of closing costs. The same quarter-point on $700,000 is a different conversation entirely — loan size matters as much as the rate change.
You are consolidating short-term debt into a 30-year mortgage. A cash-out refinance to clear credit cards lowers the interest rate, but converts unsecured debt into debt secured on your home and stretches it over decades. The monthly number improves; the total often does not, and the downside if you cannot pay is now your house.
Rate-and-Term vs Cash-Out
Rate-and-term refinancing replaces your loan with a new one at a different rate, term, or both. You borrow roughly what you owe. This is the standard case and gets the best pricing.
Cash-out refinancing borrows more than you owe and hands you the difference. It is normally the cheapest large sum you can borrow, because it is secured on your home — but that is exactly the risk, and lenders price cash-out slightly higher than rate-and-term, typically requiring you to keep at least 20% equity.
The calculator handles both. Enter a cash-out amount and it is added to the new balance, raising the payment and the interest. It is deliberately excluded from the lifetime interest comparison, because cash-out is money you received rather than a cost you incurred — counting it as a loss would make every cash-out look like a mistake, which is not the question you are asking.
Comment nous calculons cela
- Méthode
- Amortised payment comparison with break-even
- Formule
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Payment = P × r ÷ (1 − (1 + r)^−n), r = annual rate ÷ 12, n = months — the same standard amortisation formula the amortization calculator uses. Break-even month = closing costs paid up front ÷ monthly saving. Lifetime difference = interest still owed on the current loan − (interest on the new loan + closing costs). Rolled-in costs and any cash-out are added to the new principal instead of being charged up front. - Source
- Standard amortising-loan formula, shared with public/js/calculators/amortization-engine.js so the two pages cannot disagree about a payment.
- Limites
- Principal and interest only. Property tax and home insurance follow the property rather than the loan, so they are identical under both options and would cancel out of the comparison. PMI is NOT modelled — if your equity has passed 20%, dropping PMI can be worth more than the rate change itself. Assumes a fixed rate, that you keep the new loan for its full term, and that no extra payments are made. Cash-out is excluded from the interest comparison because it is money received, not a cost. The break-even figure is only meaningful when the payment falls and something was paid up front; with rolled-in costs there is no cash outlay to recover and the page says so rather than printing a misleading number.
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