Interest-Only Mortgage Payment Calculator View Calculator Calculate the payment amount for an interest-only mortgage loan. An interest-only loan pays no principal in the early years of the loan then converts to a traditional amortized loan for the remainder of the mortgage length. The payments are lower during the interest-only period since no principal is being paid. The payment goes up sharply after the interest-only period since you must pay the balance of principal plus interest during the remaining loan years. Enter your sale price, any down payment you're making, the length of the loan, and the points and closing costs. Then enter the interest rates, lengths, and any additional principal amounts you plan to pay each month for the interest-only and amortized periods of the loan. This calculator will then show you the monthly payment amounts for the interest-only and amortized periods. It will also calculate the total amount of interest you will pay, the total amount of money you will spend over the life of the loan, and the anticipated payoff time. You can also display and/or print the full amortization schedule for your loan. Learn more about putting this calculator or other calculators on your website.