Auto Loan Calculator
Adjust the inputs below. Results update as you type.
How it works
Uses the standard amortization formula with your loan amount (purchase price minus down payment and trade-in), APR, and term in months. Longer terms lower the monthly payment but increase total interest paid. Sales tax is typically financed too—add it to the loan amount if not paying upfront. Manufacturer incentive rates may require forgoing a rebate; compare both scenarios.
Input guidance
- Loan amount should be price minus down payment and trade-in, plus any financed fees or tax.
- Use the APR from the offer you are comparing, not a marketing teaser alone.
- Shorter terms raise payment but usually cut total interest.
The formula
Car payments amortize like any fixed loan: M = P · r · (1+r)^n / ((1+r)^n − 1). P is the price minus down payment and trade-in plus tax and fees financed, r is the monthly rate, n is the number of months.
Worked example
A $28,000 car with $3,000 down at 7% for 60 months finances $25,000: monthly payment ≈ $495, total interest ≈ $4,700.
More examples to test
- $32,000 financed at 6.9% for 60 months: estimate payment and total interest.
- Compare the same loan at 48 vs 72 months and note interest difference.
How to interpret results
Compare total interest and payment comfort together. A lower payment from a longer term can cost more overall.
When this can be inaccurate
Dealer add-ons, gap insurance, and rate markups can change the financed amount and APR after the sticker price.
Change history
- July 2026: Published with financed-tax guidance and term tradeoff notes.
Site-wide corrections also appear on the corrections log.
Frequently asked questions
Should I include sales tax?+
If you finance the tax (common in the US), add it to the amount borrowed. If you pay tax upfront, leave it out of the loan amount.
Is a longer auto loan a good idea?+
Long 72- or 84-month loans lower the payment but you risk owing more than the car is worth (being upside down) because cars depreciate faster than the balance falls.
How does the down payment help?+
A bigger down payment reduces the amount financed, lowering both the monthly payment and total interest, and helps you avoid negative equity.
Should I take a longer term for a lower payment?+
Only if the payment is necessary and you accept higher total interest. Compare lifetime cost, not payment alone.
Do I include sales tax in the loan amount?+
Include tax and fees only if they will be financed. Paying them upfront reduces the amount financed.