A shorter amortization schedule means you save on interest but need to pay more each month. It all comes down to what you can afford.We will help you better understand how to calculate mortgage interest rates and payments prior to purchasing your dream home. This tool figures a loan's monthly and balloon payments, based on the amount borrowed, the loan term and the annual interest rate. A balloon loan is usually rather short, with a term of three to five years, but the payment is based on a term of up to 15 years. A balloon payment is a large one-time amount due at the end of a loan. Mortgages, auto loans, and business loans have been structured for balloon payments. There are also adjustable rate mortgage (ARM) loans where the interest rate can change during the loan term.