The tutorial shows how to build an amortization schedule in Excel to detail periodic payments on an amortizing loan or mortgage. Make math easier with these free calculator templates.This Excel spreadsheet makes it easy to view the amortization of a home loan with optional extra monthly payments. This spreadsheet creates an amortization schedule for a fixed-rate loan, with optional extra payments. Enter your mortgage details here. Enter extra payment amount in relevant month rows. You can just type additional payments directly in the Extra Payment column. Fill out cells B1-B3 with details about your loan. Leave B4 (the cell next to the Payments label) blank. Students get a hands-on way to learn how loans work in the real world.