Auto Loan Calculator

Reading the result

The dominant figure is the monthly payment. Underneath it, total loan amount is what you actually borrow after your down payment, trade-in and any rebates; upfront payment is what you hand over on the day, which includes sales tax and fees unless you tick "Include taxes and fees in loan". Total cost adds the price, the interest, the tax and the fees together — the number worth comparing between deals.

The loan breakdown shows how much of everything you repay is principal and how much is interest. On a $40,000 loan over 5 years at 5%, interest is about 12% of the total; push the term to 7 years and that share climbs sharply, which is the clearest argument for the shortest term you can afford.

The amortization schedule shows every payment. The chart above it plots the falling balance against the interest and the total you have paid so far, all in dollars on one axis, so you can see the moment the loan crosses from mostly-interest to mostly-principal.

How to use this calculator

1. Enter the vehicle price, the loan term in months, the annual interest rate and your down payment.
2. Set the sales-tax rate for your area and any additional fees (title, registration, documentation).
3. Open Trade-in & fees to add a trade-in value and the amount still owed on it.
4. Use the Finance taxes and fees in the loan checkbox to roll tax and fees into the balance or pay them upfront, then calculate.

The result shows the amount financed, the monthly payment, the interest over the term, the cash due upfront and the car's true total cost once financing is included.

What actually gets financed

The monthly payment is driven by the amount financed, not the sticker price. Your down payment and any trade-in equity reduce it, while sales tax and fees can either be added to it or paid separately. Trade-in equity is the car's value minus any loan you still owe on it — positive equity works like extra cash down, and negative equity (owing more than it is worth) is added to the new loan.

The formula

First the calculator works out the amount financed, then it amortizes that balance:

Financed = price + tax + fees − down payment − trade-in equity

M = P · r · (1 + r)ⁿ / ((1 + r)ⁿ − 1)

• P — the amount financed (the line above)
• r — the monthly interest rate (annual rate ÷ 12)
• n — the number of monthly payments (the term)

If you choose to pay tax and fees upfront, they are removed from P and added to the cash you bring on day one instead. Sales tax is applied to the full vehicle price.

A worked example

Buy a $35,000 car with $5,000 down at 6% over 60 months, with a 7% sales tax and $500 in fees, and choose to finance the tax and fees. Sales tax is $35,000 × 7% = $2,450, so the amount financed is $35,000 + $2,450 + $500 − $5,000 = $32,950.

That gives a monthly payment of about $637.02 and roughly $5,271 of interest over five years. The car's total cost — price, tax, fees and interest — comes to about $43,221, with only your $5,000 down payment due upfront.

Finance the tax and fees, or pay them upfront?

Rolling tax and fees into the loan lowers the cash you need today but means you pay interest on them. Paying upfront costs more on day one and saves interest. Using the same car:

Approach	Amount financed	Monthly payment	Total interest	Cash upfront
Finance tax & fees	$32,950	$637.02	$5,270.95	$5,000
Pay tax & fees upfront	$30,000	$579.98	$4,799.04	$7,950

Financing the $2,950 of tax and fees adds about $472 of interest here and roughly $57 to the monthly payment — the price of keeping about $2,950 in your pocket today.

How sales tax is estimated

This calculator applies the sales-tax rate to the full vehicle price and does not apply a trade-in tax credit. Tax rules vary by jurisdiction — some states tax the price after a trade-in, and rebates and fees can be treated differently — so treat the sales-tax figure as a planning estimate and confirm the exact amount with your dealer or state.

Tips and limitations

• A common guideline is about 20% down on a new car and 10% on a used one, which lowers the payment and helps you avoid owing more than the car is worth.
• Longer terms (72–84 months) shrink the payment but raise total interest and the risk of going underwater as the car depreciates.
• Dealers may mark up the financing rate, so a pre-approval from a bank or credit union gives you a rate to beat.
• The tool does not model gap insurance, extended warranties, depreciation or dealer add-ons, so confirm the final figures on your contract.

To compare a plain fixed-rate loan without the tax-and-trade-in machinery, see the loan calculator; to watch each payment split between principal and interest, use the amortization calculator. This is an estimate for planning, not a financing offer or financial advice — your actual rate, taxes and fees depend on the lender, dealer, location and your credit.