US Mortgage Refinance Calculator
Compare a replacement mortgage with your remaining loan. A lower monthly payment can come with more years of interest, so both outcomes are shown.
Rule year: 2026 · USD · Sources checked
Monthly payment reduction, excluding escrow
Fixed-rate fully amortizing loans, unchanged property and no cash-out. Current term and rate are known; costs are supplied. No escrow, tax effects, PMI changes, lender eligibility, penalties, future rate changes or discounted cash-flow comparison. Simple payment break-even excludes changing payoff balances.
For informational purposes only. This estimate is not financial advice, a tax return, a payroll calculation or a lender decision. See the supported circumstances and exclusions below.
How this calculator works
Refinancing replaces the existing balance with a new amortizing loan. Paying closing costs upfront keeps the replacement principal unchanged; financing them adds to debt and creates additional interest. This calculator compares the monthly principal-and-interest amounts, a simple upfront-cash break-even where meaningful, and interest plus fees over each loan’s remaining term. A longer replacement term may reduce payments while increasing total financing cost. When costs are financed, zero upfront cash does not mean the refinance is free.
Formula and rules
Replacement principal = current balance + financed closing costs. Monthly reduction = existing payment − replacement payment. Remaining financing-cost difference = new interest + closing costs − old remaining interest.
Assumptions and limitations
Fixed-rate fully amortizing loans, unchanged property and no cash-out. Current term and rate are known; costs are supplied. No escrow, tax effects, PMI changes, lender eligibility, penalties, future rate changes or discounted cash-flow comparison. Simple payment break-even excludes changing payoff balances.
Worked example
At zero interest, a $240,000 balance with 20 remaining years has a $1,000 payment. Replacing it with the same term and financing $2,400 fees raises principal to $242,400 and payment to $1,010.
- Monthly payment reduction, excluding escrow
- -$10.00
- New monthly principal and interest
- $1,010.00
- New financed principal
- $242,400.00
- Upfront closing costs
- $0.00
Official sources and review
Reviewed against the sources below on 2026-10-07. Rates are held in versioned rule modules. Versioned rules, official source review and year-specific calculation tests.
- CFPB: refinancing your mortgage ↗
Refinancing replaces an existing loan; compare costs, rates and changed repayment terms.
- CFPB: discount points and lender credits ↗
One discount point costs 1% of loan amount; lender rate reduction must be entered, not assumed.
- CFPB: Debt-to-income ratio ↗
DTI compares monthly debt payments with gross monthly income; lending requirements vary.
Common questions
Why can a smaller payment cost more overall?
Restarting or extending the repayment term can add interest years. Review the remaining interest-plus-fees comparison as well as monthly cash flow.
Does financing closing costs make them free?
No. They increase the new balance and can accrue interest. The calculator shows the added principal.
Is this a lender approval estimate?
No. Credit, equity, property, income and lender requirements are not evaluated.