This equation will compute a bi-weekly payment,  meaning these calculations are for payments made every two weeks.

It will take as an input a payment number, and a requested output variable (which includes your choice of either Interest, Principal, or Combined). The equation will output the Interest or principal paid for that payment number in the Amortization.

Inputs

• P - the original principal amount of the loan
• r - the fixed interest rate
• n - the number of years of the loan
• choice - choice of displaying results as principal, interest or combined
• pymnt num - number of the payment for which the equation will generate the chosen output
• extra_pymnt - an optional extra payment amount

Description

An Amortization table will show, for each payment of a loan, the amount applied to principal and  the amount paid as interest.

For a standard fixed rate mortgage, the payment in the beginning is applied more towards the interest than to the principal. As the loan matures, the payment amount each month applied to principal increases, and the amount paid as interest decreases.

Usage

This equation can be used to calculate an Amortization table by month. It will return as a result the requested choice of amortization data for the requested payment period.

The equation will allow you to choose one of the following as output amortization data: 

• the Interest paid for the payment period
• the amount applied as principal for the payment period
• the combined (total) payment for the payment period