Interest-Only Mortgage Comparison Calculator View Calculator Calculate and compare (formatted side by side) the payment amounts for up to 4 interest-only mortgage loans. Enter your sale price, any down payment you're making, the interest rates and the lengths for the interest-only and amortized periods for each loan. This calculator will then show you the interest-only and amortized (after interest-only period) payment amounts, the total amount of interest you will pay and the total amount of money you will spend over the life of each loan. You can also enter the points and other closing costs and roll those into your loans. You can even enter additional payment amounts during the interest-only and amortized periods and the calculator will show you each loan's anticipated payoff time. Learn more about putting this calculator or other calculators on your website.