Should I Refinance My Mortgage? How to Know If the Math Works
Refinancing can save thousands — or cost you more than you gain. Here's how to run the actual numbers for your specific situation before you commit to anything.
Every time mortgage rates shift, the question resurfaces: should I refinance? Your inbox fills up with mailers from lenders promising to slash your payment. A neighbour mentions they just locked in a better rate. And suddenly you're wondering whether you're leaving money on the table every single month.
Here's the honest answer: refinancing can be one of the smartest financial moves a homeowner makes — or a costly mistake that resets your loan progress and takes years to recover. The difference comes down entirely to whether you've run the actual math for your specific situation, not someone else's.
What Does Refinancing Actually Mean?
Refinancing replaces your existing mortgage with a brand-new loan — new terms, new interest rate, new closing costs, and a reset amortisation schedule. Your old loan is paid off; a new one begins. Most homeowners refinance for one of four reasons:
Rate-and-term refinance — Securing a lower interest rate, shorter loan term, or both, without taking cash out
Cash-out refinance — Borrowing against accumulated home equity in exchange for a lump sum
Removing PMI — Refinancing out of an FHA loan (with permanent MIP) into a conventional loan once sufficient equity exists
Switching loan type — Moving from an adjustable-rate mortgage (ARM) to a fixed-rate loan for payment stability
This guide focuses primarily on the rate-and-term scenario — the most common situation homeowners face.
The Break-Even Point: The Only Number That Matters First
Before you think about monthly savings, you need to think about the break-even point — the number of months it takes for your cumulative monthly savings to outweigh the upfront cost of refinancing.
Refinancing isn't free. Just like your original mortgage, a refinance comes with closing costs — typically 2% to 5% of the new loan amount. On a $280,000 loan, that's $5,600 to $14,000 due at closing or rolled into the new loan balance.
Break-even formula
Total refinance closing costs ÷ Monthly payment savings = Break-even point in months
Real example:
Current payment: $1,980/mo → New payment: $1,740/mo → Monthly savings: $240
Closing costs: $7,200 ÷ $240 = 30 months to break even
Stay longer than 30 months and every month after is pure savings. Move before then and you close at a loss.
This single calculation eliminates most of the noise around refinancing decisions. Don't let a lender skip past it.
Enter your current loan details and a new rate below. The calculator shows your monthly savings, break-even timeline, and total interest comparison — everything you need before talking to a lender.
Refinance Savings Calculator
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How Much Rate Difference Justifies a Refinance?
The old "only refinance if you can drop your rate by at least 1%" guideline isn't wrong, but it's incomplete. The rate drop that makes sense depends on your remaining loan balance and how long you plan to stay.
Rate Drop
Remaining Balance
Generally Worth Evaluating?
0.5%
$350,000+
Possibly — run the break-even
0.75%
$250,000+
Likely yes
1.0%
$200,000+
Usually yes
1.5%+
Any balance
Strong candidate
These are starting filters, not rules. Your break-even calculation is still the definitive test.
The Hidden Cost Most Homeowners Miss: Resetting Your Amortisation
Mortgage amortisation front-loads interest. In the early years of a 30-year loan, the majority of each payment goes toward interest, not principal. By year 10 or 15, more of each payment is reducing your loan balance.
When you refinance into a new 30-year loan, you restart that clock. You go back to paying mostly interest again. Even at a lower rate, this can mean paying significantly more total interest over the life of the loans combined — especially if you're already 7, 10, or 12 years into your current mortgage.
⚠️ The 38-year mortgage trap
A homeowner 8 years into a 30-year mortgage who refinances into a new 30-year at a lower rate is now paying a mortgage for 38 total years. The monthly savings may look attractive — but the total interest paid over the combined loan life could actually be higher than staying put.
The solution isn't to avoid refinancing — it's to refinance into a shorter term when possible, or to make extra principal payments on the new loan to compensate. Refinancing from a 30-year into a 15-year at a lower rate often produces dramatic total interest savings, even if the monthly payment doesn't drop as much.
When Refinancing Usually Makes Sense — and When It Doesn't
✓ Usually makes sense
You bought at a rate peak and rates have dropped 1%+
You're early in your loan term (years 1–8)
You plan to stay 10+ years post-refinance
You're in an FHA loan with permanent MIP and have 20%+ equity
You can shorten from 30 to 15 years at a lower rate
✗ Probably doesn't make sense
You're selling or moving within 2–3 years
You're deep into your loan (year 20+) and won't shorten the term
Your credit has declined since your original loan
Closing costs are unusually high (4%–5% of loan)
The rate improvement is less than 0.5%
No-Closing-Cost Refinances: Worth It or Not?
Lenders sometimes advertise no-closing-cost refinances to eliminate the upfront barrier. The costs don't disappear — they're either rolled into the loan balance or offset by a higher interest rate (a lender credit).
When it can make sense
If you're short on liquid cash, fairly confident you'll sell or refinance again within a few years, and the rate increase from the lender credit is modest (0.125%–0.25%), a no-closing-cost structure may be worth it. In most other cases, paying upfront and locking the lowest possible rate produces better long-term economics.
If a lender leads with "no closing costs" before discussing your break-even or total interest savings, treat that as a prompt to ask sharper questions.
What You Need to Qualify for a Refinance
You'll go through a qualification process similar to your original mortgage application:
Credit score — Most conventional refinances require 620 minimum; better rates typically need 740+
Equity — At least 3%–5% for a rate-and-term refi; 20% to avoid PMI; 20%+ remaining after any cash-out
DTI ratio — Same 43% back-end limit most lenders apply to purchases
Income verification — Two years of tax returns, recent pay stubs, and bank statements
Home appraisal — Required in most cases to confirm current market value
Refinancing typically costs 2%–5% of the loan amount in closing costs — covering origination fees, appraisal, title insurance, and related charges. On a $300,000 loan, expect $6,000–$15,000 upfront or rolled into the new loan.
How long does a mortgage refinance take?
Most refinances close in 30–45 days from application, though some lenders move faster. The timeline depends on appraisal scheduling, document verification, and underwriting volume.
Can I refinance if I just bought my home?
Technically yes — there's no mandatory waiting period for conventional refinances, though some loan types require 6–12 months seasoning. Practically speaking, closing costs from your original purchase plus a new refinance in quick succession rarely pencils out financially.
Does refinancing hurt your credit score?
A refinance involves a hard credit inquiry, which typically causes a small, temporary dip — usually 5 points or fewer. Rate shopping with multiple lenders within a 14–45 day window is generally treated as a single inquiry by credit scoring models.
What's the difference between refinancing and a loan modification?
A refinance replaces your loan entirely with a new one at market rates through standard qualification. A loan modification changes the terms of your existing loan — often reserved for borrowers in financial hardship who cannot qualify for a standard refinance.
Run the Math Before Anyone Runs It for You
Know your break-even point. Understand what resetting your amortisation costs. Compare total interest — not just monthly payments. Use the calculator above to get the full picture.