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 mortgage is a home loan with an initial period of low or no monthly payments and a large payment at the end.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. This calculator computes the payment amount necessary for a mortgage with a balloon payment, using monthly interest compounding and monthly payments. A balloon mortgage is usually rather short, with a term of five to seven years, but the payment is based on a term of 30 years.