Auto Loan Calculator
Estimate your monthly car payment, total interest, and total cost — including tax and trade-in.
Enter your loan details
Updates liveEstimates only. Excludes title, registration, and dealer fees. Sales tax rules vary by state.
Understanding your auto loan payment
An auto loan payment depends on more than just the sticker price — your down payment, trade-in value, local sales tax, interest rate, and loan term all interact to determine both your monthly payment and how much you'll pay in total over the life of the loan.
Use this calculator to compare financing scenarios before you visit a dealership, so you can negotiate from a position of knowing your numbers.
The auto loan formula
Your loan amount is calculated first:
Then the standard amortization formula converts that loan amount into a monthly payment:
What each variable means
- P — your loan amount (principal), after down payment, trade-in, and tax.
- r — your monthly interest rate (annual rate ÷ 12 ÷ 100).
- n — the total number of monthly payments (loan term in months).
- M — your resulting monthly payment.
Step-by-step: how to use this calculator
- Enter the vehicle price, including any add-ons you're financing.
- Enter your down payment and, if applicable, your trade-in value.
- Enter your local sales tax rate — check your state or local DMV if unsure.
- Enter the interest rate your lender quoted.
- Choose your loan term — shorter terms cost less overall but have higher monthly payments.
Worked example
Suppose you're buying a $32,000 vehicle with a $4,000 down payment, no trade-in, 6.5% sales tax, a 7.5% interest rate, and a 60-month term.
| Step | Value |
|---|---|
| Taxable amount (price − trade-in) | $32,000 |
| Sales tax (6.5%) | $2,080 |
| Loan amount (P) | $30,080 |
| Monthly payment (M) | $602.74 |
| Total of all payments | $36,164 |
| Total interest paid | $6,084 |
Try these same numbers in the calculator above to confirm the result.
Interpreting your results
Compare your monthly payment against your budget first — most lenders and advisors suggest keeping total vehicle costs (loan, insurance, fuel, maintenance) under 15–20% of take-home pay. Then look at total interest paid: a lower monthly payment from a longer term can cost significantly more overall, even at the same interest rate.
Common mistakes to avoid
- Forgetting sales tax, title, and registration fees when budgeting for a purchase.
- Not shopping your loan rate separately from the dealership's financing offer.
- Choosing a longer term without realizing how much more interest accrues over time.
- Overestimating trade-in value — get an independent appraisal before relying on a number.
Frequently asked questions
What's included in my auto loan amount?
Your loan amount (the principal you actually borrow) is the vehicle price, minus your down payment and trade-in value, plus sales tax on the taxable portion of the purchase. Title, registration, and dealer fees are usually separate and are not included in this calculator unless you add them to the vehicle price yourself.
Do all states tax the full vehicle price?
No. Many states reduce the taxable amount by the value of a trade-in, which this calculator assumes by default. A few states tax the full purchase price regardless of trade-in. Check your state's Department of Motor Vehicles or Department of Revenue for the exact rule where you live.
Should I make a bigger down payment on a car loan?
A larger down payment reduces your loan amount, your monthly payment, and your total interest paid. It also helps you avoid being 'upside down' — owing more than the car is worth — since vehicles depreciate quickly in the first few years.
How does loan term affect my total cost?
A longer term (72 or 84 months) lowers your monthly payment but increases total interest paid and the risk of owing more than the car is worth for longer. A shorter term (36 or 48 months) raises the monthly payment but reduces total interest significantly.
Does my credit score affect the interest rate I should enter?
Yes, significantly. Auto loan rates vary widely by credit tier — borrowers with excellent credit often qualify for rates several percentage points lower than those with fair or poor credit. Use the rate quoted by your lender, or shop multiple lenders for a more accurate estimate.
Related calculators
Conclusion
The best auto loan isn't necessarily the one with the lowest monthly payment — it's the one with the lowest total cost that still fits your budget. Run a few different down payment and term combinations above before you negotiate at the dealership.