This tool figures a loan's monthly and balloon payments, based on the amount borrowed, the loan term and the annual interest rate. Mortgages with adjustable rates, interest-only payments, negative amortization, or balloon payments are not permitted.The program reserves the right to. 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. Down Payment Assistance Loan for. Use the balloon payment calculator to estimate the monthly payment and the final lump sum of a given balloon loan construction. This calculator computes the payment amount necessary for a mortgage with a balloon payment, using monthly interest compounding and monthly payments.