US Mortgage refinance calculator
Compare your current loan against a refinance to see break-even point and lifetime savings.
Current loan
New loan
| Current | New | |
|---|---|---|
| Monthly payment | $1,925.88 | $1,589.81 |
| Remaining interest | $343,985.71 | $292,331.31 |
Total interest saved over the full loan life, minus what you pay in closing costs. Negative means refinancing costs you more over the long run — but you may still benefit from lower monthly payments.
How a refinance break-even is calculated
The break-even point of a refinance is the number of months it takes for your reduced payment to recoup the upfront closing costs:
Break-even months = closing costs ÷ monthly savings
If a refinance costs $4,800 and saves $200/month, you break even at 24 months. After that point, every additional month is pure saving; before it, you've lost money relative to keeping the existing loan.
Worked example
- Current mortgage: $300,000 balance at 7.5% over 30 years remaining → $2,098/month
- New mortgage: $300,000 at 6.0% over 30 years → $1,799/month
- Closing costs: $5,000
- Monthly savings: $299
- Break-even: $5,000 ÷ $299 = 16.7 months
- Lifetime interest saved if you stay the full new term: ~$107,700
When refinancing makes sense
Two conditions must hold: (1) your monthly savings × months you'll stay in the home must exceed closing costs, and (2) the lifetime interest savings should be material enough to make the paperwork worthwhile. A rough rule of thumb is a rate drop of 0.5–0.75 percentage points combined with 3+ more years in the home.
The "reset the clock" trap
Refinancing from a 30-year mortgage you're 5 years into, into a fresh 30-year mortgage, means paying interest for 35 total years on the property. Lower monthly payment, but potentially more lifetime interest. Two ways to avoid this: refinance to a 15- or 20-year term, or keep the new mortgage but pay extra each month to mimic the old payoff schedule.
Common mistakes
- Looking only at the monthly payment delta. A lower payment achieved by extending the term may cost more in lifetime interest.
- Forgetting the time horizon. Closing costs matter only if you'll stay long enough to recoup them.
- Ignoring opportunity cost of the closing costs. $5,000 invested at 7% for 25 years grows to about $27,000.
- Skipping the rate-lock window. Rates can move 0.25–0.50 percentage points in a week. Always lock once committed.
What this calculator doesn't cover
- Cash-out refinance (additional principal beyond the existing balance)
- ARM-to-fixed conversions with rate-cap modelling
- Tax treatment of mortgage interest deduction differences
- Specific points/buy-down economics
Related calculators
Frequently asked questions
When does refinancing make sense?
How do I calculate the refinance break-even point?
Are refinancing closing costs tax-deductible?
Does refinancing hurt my credit score?
Should I refinance to a 15-year mortgage?
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