How this refinance calculator works
A refinance replaces your current mortgage with a new loan. The monthly save is the difference between the two principal-and-interest payments. Break-even is closing costs divided by that monthly save: how many months until fees are recovered. If you sell or refinance again before that month, the “cheaper payment” can still be a net loss.
This page amortizes both loans with the standard fixed-rate formula. It does not add a new escrow (tax and insurance stay on the PITI calculator). Lifetime difference is remaining interest on the old loan versus interest on the new loan plus closing costs. Resetting a 27-year balance to a fresh 30-year term usually cuts the payment and can raise total interest — watch both lines, not only the big monthly number.
Cash-out refinances add a larger balance; treat the extra cash as a separate decision (home repairs versus a vacation). Rate-and-term refinances still fail the test when the rate drop is tiny, fees are high, or you will not keep the house long enough. This is a worksheet. A lender lock, discount points, and prepaid interest will move the real numbers.