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Refinance Break-Even Calculator
A refi is a bet that you'll keep the loan long enough for the monthly savings to pay back the closing costs. This computes the break-even month — and the comparison lenders skip: whether the new loan really costs less over its life, once the term reset is counted.
Break-even
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Monthly savings
New payment (P&I)
Lifetime interest, after costs
The lifetime tile compares loans of different lengths — all remaining interest on the current loan vs. all interest over the new one, closing costs included. That mismatch is the point of the comparison, but keep it in mind.
The two questions a refi has to answer
Question one: how fast do I get my money back? Closing costs are paid up front; savings arrive monthly. Divide one by the other and you get the break-even month. Before it, the refi has cost you money; after it, every month is profit. The whole decision compresses into one comparison — break-even month vs. how long you'll realistically keep this loan. Most people don't keep a 30-year loan for 30 years; if your break-even is 4 years and you might move in 3, the "savings" are a loss.
Question two: does the new loan cost less over its life? This is where the term reset hides. Refinance 26 remaining years into a fresh 30-year loan and the payment drops for two reasons — the lower rate (real savings) and six extra years of stretching (an illusion of savings). A refi can win the monthly comparison and lose the lifetime one. The amber warning above fires whenever your inputs do exactly this.
The formulas
break-even months = closing costs ÷ (old P&I − new P&I)
Each payment comes from the standard amortization formula on the same remaining balance. Lifetime comparison: interest left on the current loan (old payment × months left − balance) vs. interest over the whole new loan, minus closing costs.
Beating the term reset
Two clean fixes if the lifetime number turns against you: refinance into a shorter term (a 15- or 20-year usually carries a lower rate than the 30 as well), or take the 30-year and keep paying your old payment — the difference becomes extra principal, the payoff date stays roughly put, and you've captured the rate cut without the stretch. The second option also keeps the lower payment available as a safety valve in a tight year.
Common questions
How big a rate drop is worth refinancing for?
Should I pay points for a lower rate?
What about a cash-out refinance?
Do I have to refinance with my current lender?
See the refi inside your whole plan
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