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 mortgage can be an excellent option for many home buyers. See how this balloon mortgage calculator can help you. This calculator computes the payment amount necessary for a mortgage with a balloon payment, using monthly interest compounding and monthly payments. Use the balloon payment calculator to estimate the monthly payment and the final lump sum of a given balloon loan construction.