Auto Loan Calculator
Estimate your car payment including down payment, trade-in and sales tax.
Educational estimate only. This is not financial, investment, tax, legal or lending advice, a quote or a guarantee. Read the disclaimer.
Your inputs
How this calculator works
Financed principal P = max(0, price − down payment − trade-in + max(0, price − trade-in) × sales-tax rate + fees). Here r is the entered annual rate ÷ 100 ÷ 12 and n is months. The APR input is used as an interest rate; fee-inclusive lender APRs can produce different payments. The model assumes a trade-in sales-tax credit, which is not available everywhere. Trade-in is treated as value applied to the purchase; an outstanding trade-in loan is not modeled. Total value + payments includes down payment and trade-in value plus all loan payments, so it is not solely cash paid. Excludes ongoing ownership costs and any unentered fees.
Dollar results are in USD and generally rounded to the nearest whole dollar; salary equivalents and percentage outputs use two decimal places. Calculations retain JavaScript floating-point precision between steps rather than rounding every payment to cents. Displayed components may not sum exactly to displayed totals. Payoff times use whole monthly payment periods. Defaults are examples, not current rates or recommendations.
Full methodology · About the publisher and corrections
Content and calculation checks: October 12, 2026. Educational estimates; no independent professional certification is claimed.
Worked example: $40,000 vehicle purchase
With a $40,000 vehicle price, $5,000 down payment, $3,000 trade-in, 7% sales tax, $500 in financed fees and a 7% rate for 60 months, the model finances about $35,090. The estimated payment is about $695 per month, with roughly $6,599 in loan interest.
The tax treatment of a trade-in varies by jurisdiction, and an outstanding loan on the trade-in is not modeled here.
Practical guide
What to compare when financing a car
- Separate the vehicle price from the financing terms so a lower payment does not hide a higher purchase price.
- Test down payment changes, but keep enough cash for registration, insurance and emergency savings.
- Include dealer or lender fees that will actually be financed.
- Compare total interest and total cost, not just monthly payment.
How to use the result
Change one assumption at a time to compare scenarios. For example, test a lower rate, larger contribution, different term or extra payment. This makes the calculator most useful as a decision-support tool rather than a single-number answer.
Important financial decisions can depend on taxes, fees, eligibility rules, lender policies, market returns and personal circumstances that this simplified calculator does not capture.
Frequently asked questions
Is this auto loan calculator free?
Yes. SumStride calculators are free to use and do not require an account.
Are the results exact?
No. Results are estimates based on the values you enter and the assumptions described on this page. Real-world fees, taxes, rates, policies and timing can differ.
Does SumStride save my inputs?
No account is required. The calculator runs in your browser; SumStride does not need your entered values to perform the calculation.