Auto Loan Calculator
The sticker price of a car is only the start. What you actually pay depends on the tax and fees added to it, how much you put down or trade in, and — above all — the interest rate and the length of the loan. This calculator builds the full picture: it adds sales tax and fees to the price, subtracts your down payment and trade-in to find the amount financed, then works out the monthly payment, total interest and the real total cost of the car. Change the term to see the classic trade-off between a lower payment now and a higher total cost later.
How to use the auto loan calculator
- Enter the vehicle price, down payment and trade-in value.
- Enter sales tax and fees. Many places tax the price minus your trade-in; check the rule where you live.
- Enter the interest rate (APR) you have been quoted, and choose a term.
- Compare terms: note how total interest grows as the loan gets longer, even when the monthly payment falls.
Formula
Amount financed = price + sales tax + fees − down payment − trade-in, where sales tax = (price − trade-in) × tax rate. Monthly payment = L × i ÷ (1 − (1 + i)−n), with i the monthly rate and n the number of months. Total interest = payment × n − amount financed.
Worked examples
A $30,000 car with a trade-in
A $30,000 car with $3,000 down, a $5,000 trade-in, 6% tax on the net $25,000 ($1,500) and $500 fees means financing $24,000.00. At 6.5% over 60 months the payment is $469.59 and total interest is $4,175.25.
Shorter versus longer
Same loan over 36 months: $735.58 a month and $2,480.74 interest. Over 84 months: $356.39 a month but $5,936.46 in interest.
The cost of a higher rate
The same 60-month loan at 11% instead of 6.5% costs $521.82 a month, with $7,309.09 of total interest — which is why checking your credit and shopping for the loan before the dealership matters.
Buying a car: what to compare
Term, payment and total cost
| Term | Monthly payment | Total interest |
|---|---|---|
| 36 months | $735.58 | $2,480.74 |
| 48 months | $569.16 | $3,319.63 |
| 60 months | $469.59 | $4,175.25 |
| 72 months | $403.44 | $5,047.56 |
| 84 months | $356.39 | $5,936.46 |
Tips
- Get pre-approved by a bank or credit union before visiting a dealer.
- Compare the out-the-door price, including tax and fees, not just the sticker price.
- Be wary of terms longer than the time you will keep the car, which can leave you owing more than it is worth.
For other borrowing, see the loan calculator and personal loan calculator.
Practice problems
Try these yourself first, then check your answer. The answers come from the calculator above.
- A $24,000 car, $2,000 down, no trade-in, 7% tax, $400 fees, 7.2% for 48 months. What is the monthly payment?
Show answer
Monthly payment: $578.86
Common mistakes to avoid
- Focusing only on the monthly payment. Dealers can hit any payment by stretching the term — compare total cost instead.
- Long terms on depreciating assets. With 72–84 months you may owe more than the car is worth for years (negative equity).
- Forgetting tax, title and fees when budgeting the down payment.
- Rolling negative equity from an old car into a new loan, which raises the amount financed.
- Not shopping the rate. Pre-approval from a bank or credit union gives you something to compare with the dealer’s offer.
Frequently asked questions
How is a car payment calculated?
From the amount financed, the interest rate and the term using the standard amortisation formula. The calculator shows each step and the total interest.
How much should I put down on a car?
Many advisers suggest around 20% on a new car to offset immediate depreciation and reduce interest, but the right figure depends on your finances.
Is sales tax charged on the trade-in value?
In many US states, tax applies only to the price minus the trade-in; in others it applies to the full price. Rules differ, so check your local rate and rule.
What is a good loan term for a car?
Shorter terms (48–60 months) cost less interest overall. Longer terms lower the payment but raise total cost and increase negative-equity risk.
What interest rate should I expect?
It depends on your credit, the lender, the age of the car and the market. Get quotes from several lenders to see your real rate.
Is this financial advice?
No. It is an educational estimate; your lender’s paperwork has the binding numbers.
By Thomas M, Registered Investment Adviser (South Carolina), who launched his own financial advisory firm in 2010. Last reviewed September 26, 2026. Found a mistake? Tell us; see our editorial policy.