Mortgage Calculator Purchase & Financing Information Sale Price of Home: $ Percentage Down: % Length of Mortgage: years Annual Interest Rate: % Explain Calculations: Show me the calculations and amortization   This mortgage calculator can be used to figure out monthly payments of a home mortgage loan, based on the home's sale price, the term of the loan desired, buyer's down payment percentage, and the loan's interest rate. This calculator factors in PMI (Private Mortgage Insurance) for loans where less than 20% is put as a down payment. Also taken into consideration are the town property taxes, and their effect on the total monthly mortgage payment.