How Amortization Works

by : Richard Romando



An amortized loan can be a car loan or a home loan, as long as it is for one specific amount that is to be paid off by a certain date in equal installments. Parts of the payment go toward the interest cost and the remainder goes toward the principal amount. Interest calculated is based on the current amount owed. As the ending balance of the loan reduces, the interest also decreases progressively, termed as "amortization".

Like mortgages, with an amortized loan during the first few months/years of the loan term, a greater percentage of the payment goes toward interest in comparison to principal balance or the amount borrowed. This can be explained with a mortgage loan for $100,000 at 6.5 percent for 30 years as an example:

The monthly principal and interest payment is $632.07. For the first month, the interest owed for $100,000 is equal to $541.67. The remainder of the payment, $90.40, goes toward principal, thereby reducing the debt by that amount.

The interest owed drops down to $99,909.60 in the second month, so $541.18 goes to interest and $90.89 goes to principal. The interest goes on decreasing with each passing month while the principal reduction increases, and continues until $3.41 goes to interest and $628.66 to principal on the 360th payment.

Basically, half the loan has been paid off after 256 payments (21 years and 4 months). The other half can be paid off in 8 years and 8 months. A typical amortization schedule calculator would produce an amortization table displaying how much interest and how much principal, from the first to the last, is included in each monthly payment.