The Mechanics of Amortized Loans: Auto & Personal
Taking out a personal or auto loan involves an amortized repayment schedule. This means your monthly payments remain fixed over the life of the loan, but the proportion of principal versus interest within that payment changes over time.
How Amortization Works
In the early months of your loan, a larger portion of your fixed monthly payment goes toward paying off the interest. As the principal balance gradually decreases, the interest charge shrinks, and more of your payment is applied directly to the principal.
The Standard Loan Formula
Lenders use a standard mathematical formula to calculate your exact monthly payment based on the principal amount, the interest rate, and the length of the term:
The True Cost of Longer Loan Terms
While extending an auto loan from 36 to 72 months will drastically lower your monthly payment, it significantly increases the total amount of interest you will pay over the life of the loan. Additionally, because vehicles depreciate rapidly, exceptionally long loan terms can leave you 'underwater'—meaning you owe more on the loan than the car is actually worth.
Calculate Your Options
Use the calculator on the left to see how adjusting your loan term or securing a lower interest rate affects both your monthly budget and your total cost of borrowing.