The tutorial shows how to build an amortization schedule in Excel to detail periodic payments on an amortizing loan or mortgage. I want to set the formulas to calculate the details (interest paid, balance, etc.) based on biweekly payments.Loan amortization schedule. 3. 4, Enter values, Loan summary. I'm looking for a Biweekly Loan Amortization Schedule that will allow me to input various additional payments depending on ability. A biweekly amortization schedule is a table that details your loan payments every two weeks instead of the traditional monthly payment schedule. This calculator will help you to figure a current loan balance when the borrower made different payments than those stipulated in the original loan terms.