How to read a mortgage refinance
What this calculator does
A refinance replaces your existing mortgage with a new one, usually to capture a lower rate, change the term, or free up monthly cash. This tool compares your current loan with a proposed new loan so you can see the trade-offs side by side — not just the new payment, but the break-even point and the cost over the whole life of the loan.
It compares principal and interest, the part a refinance actually changes. Escrow items such as property taxes and homeowners insurance stay roughly the same regardless of your rate, so leaving them out keeps the comparison clean and honest.
When a refinance makes sense — and when it doesn’t
Refinancing tends to make sense when the rate drop is meaningful, you plan to stay in the home past the break-even point, you are not stretching the term out much longer than you have left, and your credit qualifies you for the quoted rate. Refinancing into a shorter term — say from 25 years left to a 15-year loan — often raises the payment but cuts total interest sharply.
It may not make sense if you plan to move or refinance again before the break-even point, if the monthly payment does not actually fall, or if the only way to lower the payment is to reset to a much longer term. High closing costs relative to the balance take longer to recover, and a cash-out refinance adds debt that raises the long-run cost.
Paying for the refinance: cash, rolled in, or no-closing-cost
Closing costs typically run a few percent of the loan — lender or origination fees, title and escrow, appraisal, recording, and other charges — and discount points, each one percent of the loan, can buy a lower rate on top. You can pay all of this in cash, roll it into the new balance, or choose a no-closing-cost refinance where the lender absorbs it in exchange for a higher rate.
None of these options is free. Paying cash means a real break-even to recover; rolling costs in raises the balance and the interest you pay on it; a no-closing-cost rate is higher for the life of the loan; and points only pay off if you keep the loan long enough to recover them. The calculator lets you model each so you can see the upfront-cash and lifetime-cost effect of every choice.
The same-term comparison
When you can, compare the new loan against your current remaining term rather than a brand-new 30 years. Matching the term isolates the effect of the rate alone, so you can see the pure rate benefit without the distortion of a longer schedule. Turn on the same-remaining-term comparison in the calculator to see this side by side with the base refinance.
Worked example
Suppose you owe $350,000 at 7.5% with 25 years left, and you are offered 6.5% on a fresh 30-year loan with $6,000 in closing costs paid in cash.
Current payment
$2,586 / mo
5-year net saving
≈ +$16,440 cash flow
Lifetime cost difference
−$26,464 (extra cost)
The lower payment recovers the $6,000 of costs in about 17 months — good for monthly cash flow, and within five years you would be roughly $16,000 ahead on payments. But stretching a 25-year balance back out to 30 years adds five more years of payments, so the lifetime total is roughly $26,000 higher even at the lower rate. This is the classic trap: a lower payment is not the same as a lower cost. A same-term comparison (6.5% over the 25 years you have left) would instead show a real lifetime saving, because it captures the rate benefit without resetting the clock.
When this calculator may be wrong
This is a planning estimate, not a lender quote. The relative comparison is reliable, but the absolute figures can differ from your real loan because:
- It compares principal and interest only — taxes, insurance, escrow, and HOA are not included unless you add them elsewhere.
- It does not calculate the lender's APR or finance charge, which fold in fees differently.
- It assumes a fixed rate and the figures you enter; adjustable-rate loans and lender-specific fees can change the outcome.
- It does not model the tax treatment of mortgage interest, mortgage-insurance changes, or prepayment penalties.
- Advertised rates often assume excellent credit and points paid upfront, so the rate you qualify for may differ.
Verify before deciding: confirm the rate, points, fees, and cash-to-close on a lender's official Loan Estimate, and consider speaking with a qualified mortgage or financial professional.
Sources & methodology
This calculator uses standard fixed-rate amortization for both loans and the Federal Reserve break-even approach (upfront cash ÷ monthly saving). Closing costs, points, cash-out, and rolled fees are user-entered estimates, not a lender quote. Links open in a new tab.