The decision to buy a car, new or used, is a big one for most of us. It involves an accurate inventory of the finances and a precise estimate of the projected expenses. One quick and easy application you can use to lessen your number crunching is an auto loan calculator. It will calculate the monthly payment you will need to make based on the sum you want to borrow, prevailing interest rate and the duration over which you want to repay the loan.

There are a few calculators that need you to download the application before you can use them, but for a good approximation, here are the top five available online without a download.

5) Auto Loan Calculator at Cars.com

This popular website for information on car pricing also offers a auto loan calculator that is easy to use. The navigation is simple, but the information required is a touch more than the other calculators. In addition to the interest rate and term, you have to enter the vehicle price, down payment amount, trade in value and sales tax percentage.

4) Auto Loan Calculator at Edmunds.com

Like the calculator from Cars.com, this also requires more details as compared to the other options. The benefit here is that if you have a vehicle that you want to trade in, you can ‘Select A Vehicle’ and get an estimate of the value. There is also a Low APR vs. Cash Back comparison in case you are undecided.

3) Auto Loan Calculator at Frograte.com

You can estimate your monthly payment quickly with this easy to use application. They also provide you an HTML code that you can put on your website and offer the same calculator to your online visitors. The code is modifiable for you to give it a personal touch.

2) Auto Loan Calculator at Bankrate.com

The simple calculator asks you for basic information such as the loan amount, term, rate and start date of the loan. The other helpful feature is the calculation of an Amortization Table; you can use this feature to see how much of your payment goes towards the interest and what is the balance of the principal that is due month on month. You can also use this to chart the due amount in case you want to make extra payments beyond your monthly due.

1) Auto Loan Calculator at USAA.com

A friendly interface and an added feature to calculate the total loan amount puts the USAA auto loan calculator in the number one spot. The details required to arrive at your monthly payment remain the same as the other calculators (amount, term and rate). The feature to calculate total loan amount is great because it lets you reverse calculate the loan you can take based on the monthly sum that you can afford to pay. Details required for this feature are your monthly payment amount, rate and tenure of the loan you want to borrow.

It is important to note that these tools should be used only as a good indicator of what to expect. While their calculations should not be way off the actual numbers, you can expect a slight variance.