Mortgage Refinance Calculator
Compare your remaining mortgage with a proposed refinance, including points, closing costs, cash-out, payment savings, lifetime interest and break-even timing.
Current mortgage
Mortgage refinancing
Live refinance results
Payment summary
| Measure | Current loan | New loan | Difference |
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How to use this mortgage refinance calculator
What this calculator does
This calculator estimates whether replacing an existing fixed-payment mortgage with a new loan may reduce the monthly principal-and-interest payment or total remaining interest. It reconstructs the current balance from the original amount, start date, term, rate and compounding convention, then compares that remaining obligation with a proposed refinance. It also estimates points, other closing costs, cash-out or cash-in, and the month when cumulative payment savings recover the upfront refinance cost. It is a planning model, not a lender quote, approval decision, tax opinion, appraisal or promise that a refinance will be beneficial.
When to use it
- Compare a lender's lower-rate offer with keeping your existing mortgage.
- Test whether extending or shortening the term changes payment and lifetime interest in a way you can accept.
- Estimate how points and closing costs affect break-even timing.
- Evaluate a cash-out or cash-in structure before requesting formal Loan Estimates.
How to calculate
- The calculator opens with a complete demonstration scenario and an immediately available example XLSX workbook. Replace each sample with figures from your latest mortgage statement and lender proposal.
- Enter the current-loan details first. Then enter the proposed term, rate, compounding frequency, points, other costs and any cash adjustment. Results update live.
- Read the monthly change together with refinance cost, break-even date and lifetime interest. A lower payment can still accompany higher lifetime interest when the new term is longer.
- Select Download Excel to export the current validated inputs and results. Reset clears the demonstration values and results; it may disable Download Excel until a complete valid state is entered again.
Input guide
Original mortgage amount is a required USD amount above zero, such as $300,000. Use the original principal, not the home's value. A larger amount generally increases both the reconstructed balance and payments. Original loan start date and Refinance date are required calendar dates; the latter must be later. The model counts full monthly payment periods between them, so entering a closing date instead of the first-payment schedule can shift the estimate by one month. Original mortgage term is required in years from greater than zero through 50; 30 is typical. Current interest rate is a required annual nominal percentage from 0% through 30%, such as 3.50%. Current compounding frequency is required and should match the note's quoted convention; choosing monthly when the loan uses Canadian semi-annual compounding changes the effective monthly rate.
New loan term is required in years from greater than zero through 50; 25 means 300 scheduled monthly payments. A longer term usually lowers payment but can raise total interest. New interest rate is required from 0% through 30%. New compounding frequency should match the offer. Mortgage points is optional from 0% through 10%; 0.50 means half a point, or 0.5% of the new principal. The CFPB explains that one discount point equals 1% of the loan amount. Other refinancing costs is an optional nonnegative USD amount for lender, title, appraisal and similar charges. Cash out / cash in accepts positive or negative USD: positive increases the new principal and cash received, while negative represents cash contributed to reduce the new balance. Do not enter commas as decimal separators; this calculator uses U.S. decimal notation.
Output guide
Estimated monthly payment change and Monthly change show new payment minus current payment. A negative value is estimated monthly savings; a positive value is an increase. Current balance is the amortized principal remaining at the refinance date. New principal is current balance plus the cash adjustment; points and other costs are shown separately rather than financed. Current payment and New payment are monthly principal-and-interest estimates. Refinance cost equals points plus other refinancing costs. Break-even date and Break-even show when cumulative positive monthly savings first exceed that cost; “No break-even” means the new payment does not create monthly savings within the modeled term.
Remaining current interest and New loan interest compare future interest from the refinance date onward. Lifetime savings is the remaining current total payments minus the new loan's total payments and refinance cost; negative means the modeled refinance costs more over the compared lifetimes. The Payment summary table repeats principal, monthly payment, annual rate, remaining term, total interest and total payments for both loans, plus the new-minus-current difference. These are estimates driven by the exact inputs above, not recommendations.
Worked example
The opening example begins with a $300,000 mortgage dated September 5, 2021, a 30-year term and 3.50% monthly-compounded rate, evaluated on July 5, 2026. The proposal uses a 25-year term at 2.50%, 0.50 points, $2,863.55 of other costs and $2,500 cash-out. The calculator first converts each quoted rate to a monthly rate, reconstructs the balance after the elapsed monthly payments, adds the cash-out to form the new principal, and then applies the standard fixed-payment formula. The displayed payment change, interest comparison, refinance cost and break-even date are all generated from this same scenario and are also written as typed values in the startup workbook.
How to interpret a refinance comparison
A payment reduction is only one part of the decision. The CFPB mortgage key-terms guide notes that refinancing usually involves closing costs and that a lower payment can come partly from a longer term. Compare the new Loan Estimate with your current statement, consider how long you expect to keep the loan, and test a range of costs rather than relying on one optimistic quote.
Break-even is especially useful when you expect to sell, move or refinance again. The calculator uses a conservative cash-flow approach: upfront points and costs are recovered by monthly payment savings. The CFPB's research on discount points describes the same basic idea – costs are worthwhile only when cumulative savings exceed the upfront amount. Review the exact lender disclosures with the CFPB Loan Estimate explainer.
Tax treatment is outside this model. Mortgage points may not be deductible immediately in a refinance. Consult a qualified tax professional and review IRS Topic 504 on home mortgage points before treating any possible tax benefit as savings.