Refinance Calculator

Refinancing a mortgage that's 22 years into its term, into a fresh 30-year loan, will almost always drop your monthly payment. It will also almost always add tens of thousands in lifetime interest. Most refinance calculators on the web show you the first number and hide the second. This one shows both, side by side, and tells you in plain English whether the math works over the time you actually plan to stay in the house.

Everything runs in your browser. Your loan balance, the rate your lender quoted, the offer you're pricing — none of it hits a server, none of it gets logged, none of it feeds into a lead-generation funnel. There's no signup. There's no "talk to a lender" pop-up waiting for your email. The math is the whole product.

Seven things set this calculator apart from the ones at Bankrate, Zillow, Rocket Mortgage, Chase, and calculator.net. First, a plain-English verdict strip at the top synthesizes break-even against your stay horizon. "Break even in 14 months — worth doing" beats a page of raw numbers for anyone trying to make a decision. Second, matched-term comparison is visible by default, not hidden behind an advanced toggle. Matching the new loan to the months remaining on your current loan is the only honest apples-to-apples comparison for "am I actually saving money." Third, the break-even number shows as both months AND a calendar date (October 2027) because humans reason about dates, not month counts. Fourth, the lifetime-interest delta is called out in plain numbers — if the refi costs more over the full term than staying put, we say so, color-coded red. Fifth, cash-out mode folds in with the rate-and-term math on one page with a single toggle, including an LTV warning if you're reaching above 80%. Sixth, the no-closing-cost option models the real rate bump (default +0.375%, adjustable) so you can see what "free" actually costs over the life of the loan. Seventh, the amortization diff table and CSV export let you compare month-by-month how the two loans stack up.

A few things this tool won't do. It doesn't predict rates — type the rate your lender actually quoted, not the rate on a banner ad. It doesn't handle FHA streamline refinances, VA IRRRLs, ARMs, or discount points — those have specialty rules that deserve their own tools. It doesn't push you toward a specific lender because we don't have one. What it does do is give you the three numbers you need to decide, in the order a person making the decision actually reasons about them: what's my new payment, when do I break even, and what's this refinance actually going to cost me over the life of the loan.

Refinancing is two amortization schedules stacked on top of each other. The math is straightforward; the interpretation is where every calculator on the web diverges.

Monthly payment formula. Both the current loan and the new loan use the same standard amortization equation. Given principal P, monthly rate r = annualRate / 12, and total months n, the monthly payment is:

``
monthly = P × (r × (1 + r)^n) / ((1 + r)^n − 1)
``

For the current loan we feed in the remaining balance and months remaining — not the original balance. For the new loan we feed in whatever the effective principal is after closing costs are applied (see below) and the full new term.

Break-even math — the version this tool uses. The honest calculation is closing costs divided by monthly savings. A $6,000 closing-cost refinance that saves you $432/month pays for itself in roughly 14 months. There's a more precise version using cumulative interest instead of payment deltas (it accounts for the fact that more of each early payment goes to interest), but the simpler division lands within half a month of the exact answer for most real-world scenarios, and it's what NerdWallet's break-even explainer uses too. Where the simple version fails is when closing costs aren't paid at close — if you roll them into the balance or absorb them via a rate bump, there's no upfront cost to divide, and break-even becomes ambiguous. This tool reports "n/a" in those modes and points you at the lifetime interest delta instead, which captures the true cost.

Matched-term comparison — why it's the default. Almost every refinance calculator on the web defaults to "new loan same length as old loan type" — 30-year into a fresh 30-year, regardless of how many years are left on your current loan. That math looks great: lower rate, lower payment, big monthly savings. It also resets the clock. Someone 8 years into a 30-year loan who refinances into a new 30-year is now 38 years from payoff instead of 22. The "savings" on paper evaporates when you account for eight extra years of paying interest. Matched-term recomputes the new loan at the same number of months remaining on the current loan. That's the comparison that actually answers "am I saving money over the life of the loan?" This tool shows the matched-term alternative side-by-side with the fresh-term option so you can see both.

Three closing-cost styles modeled. Lenders offer roughly three variants of "here's how we handle closing costs":

- Paid at close. You write a check at closing for the origination fee, appraisal, title, escrow, and so on — typically 2% to 5% of the loan amount. The loan balance stays clean; the closing costs are out of pocket. This is the mode where break-even math is most meaningful.
- Rolled into the principal. The closing costs get added to the loan balance and you finance them at the mortgage rate over the full term. You avoid the upfront check, but you're paying interest on those costs for 30 years. The lifetime delta captures the real cost; break-even month is "n/a" because there's no upfront spend to divide.
- Lender-paid / no-cost refi. The lender covers closing costs in exchange for a higher rate — typically +0.125% to +0.500% over the otherwise-quoted rate. No check, no principal bump, but you pay more in interest every month for the life of the loan. The default rate bump in this tool is +0.375%, adjustable. Forbes and CBS MoneyWatch both rate no-cost refis as usually worse than paid-at-close for anyone staying in the home longer than about 4-5 years — but this tool shows you the math for your specific situation rather than repeating the general claim.

Lifetime interest delta — the honest metric. We compare the new loan's total interest (plus out-of-pocket closing costs if they're paid at close) against the current loan's remaining interest. If the delta is positive, the refinance costs more over its full term than just riding out the current loan. That's often the uncomfortable truth when resetting the term — the monthly relief in years 1 through 10 comes with a bill tacked onto years 23 through 30. The tool color-codes the delta red when it's positive and green when it's negative, so you know before you click anything else.

Cash-out mode math. Cash-out refinancing pulls equity out as cash by writing a new loan for more than you owe. The math is identical to rate-and-term with one twist: the effective new principal is the current balance plus the cash taken (plus any rolled closing costs). Post-refinance LTV is the new principal divided by the home value, times 100. Most conventional lenders cap cash-out at 80% LTV; FHA goes to 80% on standard cash-out, VA allows up to 100% on VA IRRRLs (which aren't quite cash-out but rhyme). This tool surfaces an LTV warning above 80% and notes that rates typically jump 0.25% to 0.75% once you cross that threshold — something most cash-out calculators don't mention.

Stay horizon — the conditional verdict. The single most important input for whether a refinance makes sense is how long you plan to stay in the house. A 14-month break-even is great if you'll be there 7 years; it's a net loss if you'll sell in 12 months. The stay-horizon input feeds into the verdict strip: if break-even exceeds stay, the tool says so explicitly in the headline and recommends skipping. This kind of conditional synthesis is what nobody else on the SERP does, and it's the thing that turns "here's a calculation" into "here's a decision."

APR vs interest rate. The rate you type is the note rate — the percentage your lender quotes and uses for payment calculations. APR is a separate disclosure (required under Regulation Z) that folds in certain closing costs amortized over the loan term. APR is always higher than the note rate. For "what's my new monthly payment," the note rate is what you want. For comparing offers with different fee structures side by side, compare APR to APR. They're different numbers answering different questions.

What this tool doesn't model. Property tax and insurance escrow (use our mortgage calculator for PITI math on a home loan). Adjustable-rate mortgages — this is a fixed-rate tool, no ARM caps, no worst-case payment stress-tests. Discount points — paying upfront for a lower rate has its own optimization math we'll build separately. FHA streamline and VA IRRRL refinances — these have specialty rules that make them not quite apples-to-apples with conventional refis. Mortgage recast — a lump-sum principal reduction that reduces your payment without touching the rate or term, which is sometimes a better move than refinancing and deserves its own tool.

Refinance calculators on the open web fall into a few camps, and each has a characteristic failure mode. Worth naming them so you know which one gave you the number you're looking at.

Bankrate has one of the strongest refinance tools on the SERP. Break-even math is correct, the amortization view is reasonable, and the page loads fast. The downside is the same as their mortgage calculator: rate-shopping CTAs and affiliate lender cards follow you around the viewport, and the page is tuned to move you into their lender-match funnel. Their break-even math also doesn't default to matched-term comparison, which means the "savings" figure can mislead anyone refinancing late in their current loan.

Zillow's refinance calculator is mobile-friendly and visually polished. Fast to a monthly-payment answer. The cash-out mode lives at a separate URL, the amortization table doesn't render on the refinance page (it's on the purchase-mortgage page), and the closing-cost estimate is a handoff to yet another calculator. Heavy "Talk to a local lender" push the moment you interact. Good for lender discovery; not built for standalone analysis.

Rocket Mortgage takes the opposite approach — minimal inputs, minimal outputs, then a firm hand toward the loan application flow. The amortization schedule is gated behind account creation, which is the same pattern as their other tools. No matched-term option, no cash-out mode on the same page, no honest no-cost modeling. The tool exists to qualify leads, and that's fine if you know that going in.

Chase's calculator is a small widget embedded in marketing content. It computes correctly but is missing most of the features above — no cash-out, no matched-term, no lifetime-interest view. Pure lead-gen surface for Chase's refinance products.

Calculator.net is the power-user option. Three-column side-by-side comparison, ability to set different terms, thorough math. Ugly 2005-era UI, dense ad load, no clear verdict output ("is this a good idea?"), and the math treats all payment-delta savings as nominal-dollar savings without surfacing the matched-term trap. If you want every knob, it's there; if you want a clear answer, you're doing the synthesis yourself.

NerdWallet and Forbes Advisor both sit somewhere between Bankrate and a bank site. Strong editorial content around the calculator — NerdWallet's break-even explainer is probably the best plain-language write-up of refinance math on the web. The calculators themselves are on the simpler side: rate change → monthly savings → break-even, with no amortization diff or matched-term view.

Our calculator is the opposite of most of these: the interactive tool is the whole page, and the surrounding content is reference material for the decisions the tool helps with. Nothing to click if you don't want it. No lender hand-off, no account, no "get pre-qualified in 60 seconds." If you want a rate quote, go get one from a lender directly — we'll happily tell you which ones to shop.

The tradeoffs we made, stated honestly:

- No live rate feed. You type the rate your lender quoted. Bankrate and Zillow pull live rates; we don't. If you want to see today's headline rates, Bankrate's rate page is a fine reference. The rate you'll actually get depends on your credit, LTV, and loan product — always type the specific number your lender gives you in a Loan Estimate.
- No lender quotes or pre-qualification. If you need those, this isn't the tool. A loan officer with your full file will give you a real Loan Estimate under Regulation Z.
- No ARM modeling. This is a fixed-rate refinance tool. ARMs have caps, margins, and worst-case payment rules that need their own calculator. That's a future tool on the backlog.
- No FHA streamline or VA IRRRL specialty rules. Both exist for a reason (they skip appraisals and have tighter underwriting), but they're not quite apples-to-apples with conventional refinancing. Use lender-specific or HUD-provided calculators for those.
- No discount points optimizer. Paying upfront to buy down the rate has its own math. We'll ship that separately when the demand shows up.
- No PITI modeling. This tool focuses on P&I deltas and closing costs. For property tax, insurance escrow, and PMI drop-off, our mortgage calculator handles the full PITI picture.

For the default case — "should I refinance this mortgage, and over what horizon does the math work" — this is the clearest path to a decision. For everything past the fixed-rate-refinance slice, we'll point you at whichever specialist tool fits.