Fill in the column titled "Period" with your payment dates. Input the month and year for the first payment loan within cell A8.Make math easier with these free calculator templates. What is an Amortization Schedule? PMT (Payment Function): It calculates the fixed monthly payment for a loan based on the interest rate, loan term, and loan amount. Microsoft Excel can help you manage your finances. Use Excel formulas to calculate interest on loans, savings plans, down payments, and more. This is the first of a two-part tutorial on amortization schedules.