This refinance calculator can help you calculate new monthly principal and interest payment when you refinance your existing mortgage. It can also show your monthly savings and how many months to be needed to recoup the closing costs of this refinance transaction. Enter current monthly principal & interest payment, the new mortgage loan amount, the new interest rate, the new loan term in years, and the closing costs, then click Calculate button, your new monthly principal & interest payment, monthly savings, and months to recoup the closing costs will be displayed.