Start with the reason for changing your loan
Refinancing replaces your existing mortgage with a new one. The goal may be a lower payment, a shorter payoff timeline, or a different rate structure. Decide which outcome matters before focusing on a quoted rate.
Compare the new loan against the remaining life of your current loan, rather than its original term. Starting another 30-year loan after several years of payments can lower the monthly amount while extending the time you pay interest.
Calculate a simple break-even point
Divide upfront refinance costs by the monthly principal-and-interest savings. For example, $6,000 in costs and $200 in monthly savings gives a simple break-even point of 30 months. If you sell or refinance again sooner, those payment savings alone would not recover the upfront costs.
Simple break-even is a useful first screen, but it does not compare remaining equity, time value of money, taxes, or all possible fees. Compare the balances and total costs at the same future date for a fuller decision.
Keep the comparison fair
Use written quotes with the same loan amount and treatment of closing costs. If costs are rolled into the loan, you are borrowing more; they have not disappeared. Lender credits may reduce cash at closing in exchange for a different rate.
The refinance tool assumes costs are paid upfront. Optional cash out is added to the new loan balance, and a like-for-like break-even is not shown when it is included. The tool separately shows new total interest and the modeled interest and cost difference; repayment of cash-out principal is excluded from that difference. Verify that the current payment and remaining term match your mortgage statement.
Consider the time you expect to keep the loan
Your likely time in the home can matter more than the lifetime interest figure. A shorter term may save interest but require a higher monthly commitment. A lower payment may offer flexibility but carry more long-term cost.
Ask lenders to explain any prepayment penalty, points, or fees. Keep enough cash for your household needs, and compare the final written disclosures before deciding.
Put the numbers in perspective.
Try your own assumptions in the refinance calculator. Change one input at a time to understand what matters most to your plan.
Sources & further reading
Consumer Financial Protection Bureau: Loan Estimate explainer
CFPB: Compare and negotiate loan offers