A budget is important for two reasons: it allows you to see where a new car will fit into your overall financial situation and, in addition, it allows you to compare different rates and terms to determine the amount of interest expense you’ll incur over the life of the loan. Both things, it turns out, can be accomplished by using the right tool – an auto loan payment calculator.

So where do you find such a tool? Most good car loan web sites have one. If the site you’re looking at doesn’t, try to find one that does because it can be an invaluable aid in saving you money.

The best auto loan payment calculator will allow you do a wide variety of calculations. A truly useful calculator should include a number of user fields that can be changed – such as monthly payment, term in months, cash down, trade allowance, amount owed on trade, total purchase price, interest rate, non-taxable fees, taxable fees as well as state sales tax rate.

You should also be able to calculate the monthly auto loan payment and, if possible, the total purchase price of the vehicle (pre-tax) to determine if there are any hidden fees in the payment (sort of a reverse calculation). The best payment calculators also include graphs that visually illustrate the decreasing balance based on months as well as how down payment amount and payment terms affect the monthly payment amount.

Finally, the auto loan payment calculator should also you to print the results so that you can compare the various payment scenarios as well as take this information with you when you visit a dealer.