Adjustable Rate Mortgage (Maximum Possible Payout) Calculator View Calculator Calculate the monthly payments for an adjustable rate mortgage (A.R.M.) loan. Note that this calculator is designed to show you the worst case scenario or maximum possible payout for an A.R.M., which is not likely to actually happen. The calculator has the interest rate always go up after the minimum length between steps and it always goes up the maximum step percent until the interest rate reaches the maximum. Enter your sale price and any down payment you're making. Then enter the initial fixed interest rate and the guaranteed fixed rate length, the maximum interest rate adjustment and the minimum length of time between adjustments, and the maximum interest rate for the loan. Also enter the length of the entire loan. This calculator will then show you the initial fixed rate monthly principal and interest payment, your maximum monthly principal and interest payment, the total amount of interest you will pay and the total amount of money you will spend over the life of the loan. You can also enter the points and other closing costs and roll those into your loan. You can even enter an additional payment amount you intend to pay each month to work down your principal and the calculator will show you the anticipated payoff time. You can display and/or print the amortization schedule for your loan. Learn more about putting this calculator or other calculators on your website.