A refinance calculator is a tool to help determine if refinancing a mortgage loan is financially beneficial. It estimates potential savings by comparing current loan details with new loan options, factoring in interest rates, loan terms, monthly payments, closing costs, and other fees to calculate monthly savings and the break-even point. Key information needed includes current loan balance, interest rate, monthly payment, new loan interest rate, loan term, closing costs, and any cash out amount. The calculator then shows estimated new monthly payment, total refinance cost, interest savings, and how long it takes to recoup refinance costs (break-even point). Popular refinance calculators from websites like NerdWallet, Zillow, and Bankrate provide these features to help users decide if refinancing their mortgage is worthwhile based on their financial goals.