How to read it
What this refinance calculator is actually comparing
The tool estimates a current principal-and-interest payment using your remaining balance, remaining term and current example rate. It then estimates a new principal-and-interest payment using the same balance and term with the new example rate you enter.
Keeping the balance and term constant helps isolate the effect of the rate input. It does not model cash-out proceeds, a term extension, discount points, escrow changes, mortgage insurance changes, or lender-specific pricing.
Break-even
Break-even is a useful screening tool, not a final decision rule
The break-even estimate shows how many months of positive monthly savings would be needed to recover the refinance costs you enter. If the new scenario does not lower the estimated monthly principal-and-interest payment, no positive break-even point is shown.
A shorter break-even period generally means there is more time for savings to accumulate, but you still need to compare the full economics of the loan, including fees, APR and how long you expect to keep the mortgage.
Costs
Use your own refinance-cost assumptions
Closing costs and lender fees can vary by loan, lender, property, credit profile and state. This calculator does not assume a standard cost. Instead, it lets you enter your own estimate so you can test multiple scenarios.
When you compare real offers, review the Loan Estimate carefully. The CFPB notes that a Loan Estimate shows key loan details, estimated closing costs and estimated cash to close, which helps you compare lenders on a like-for-like basis.
Context
A lower rate or lower payment does not automatically mean refinancing is better
Refinancing can change more than the monthly payment. A new loan may reset the clock, change the total interest paid over time, alter fees, or involve a different loan product altogether. The best choice depends on the full loan terms and your own time horizon.
That is why this tool should be used as an early planning screen. It helps you organize a scenario, but it does not replace a lender's disclosures or your own review of the total cost of the new mortgage.
What to review
Before acting, compare the real documents and the full payment picture
For a real refinance, compare the new loan type, interest rate, APR, projected monthly payment, estimated closing costs, cash to close, prepayment terms and any mortgage-insurance or escrow changes. Principal and interest are only one part of the picture.
If you are comparing multiple lenders, request Loan Estimates for the same type of loan so the costs are easier to compare. If something differs from what you expected, ask the lender to explain why before moving forward.