Enter your desired payment and let us calculate your loan amount or, enter in the loan amount and we will calculate your monthly payment. Use this calculator to determine your monthly payment and amortization schedule.Microsoft Excel Mortgage Caculator XLS Worksheet. The tutorial shows how to build an amortization schedule in Excel to detail periodic payments on an amortizing loan or mortgage. Federal Home Loan Mortgage Corp. Bring your stock market graph with you to lab. We will use this graph and your Excel file that you sent to yourself.