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.Do you need help understanding your debt financing terms? Use the balloon payment calculator to estimate the monthly payment and the final lump sum of a given balloon loan construction. Amortization. Analysis and adjustment of charges and prices. Billing at average rates (cost-plus contracts). The Anticipated Repayment Date for the Hyper-Amortization Loan is listed in Annex A. Amortization of Principal.