Loan Calculator
Work out monthly loan payments, total interest and total cost.
Auto Loan Calculator
Estimate your monthly car payment, including sales tax, a down payment and a trade-in.
Disclaimer: This calculator gives estimates only and is not financial, tax, or legal advice. Figures can differ from lender, employer, or official calculations. Please confirm important decisions with a qualified professional. See our full disclaimer.
The auto loan formula
First work out the amount financed: Amount financed = Vehicle price + Sales tax − Down payment − Trade-in value, where sales tax here is estimated on the price minus the trade-in. The monthly payment then uses the standard amortisation formula M = P × r(1+r)n / ((1+r)n − 1), with P the amount financed, r the monthly rate (annual rate ÷ 12) and n the number of monthly payments.
Worked example
A $35,000 car with a $3,000 trade-in and 7% sales tax: tax = ($35,000 − $3,000) × 7% = $2,240. With a $5,000 down payment, the amount financed is $35,000 + $2,240 − $5,000 − $3,000 = $29,240. At 7.5% over 60 months, the payment is about $585.91 per month, with about $5,914.58 of total interest.
How to use this calculator
- Enter the vehicle price.
- Add your down payment and any trade-in value.
- Enter your local sales tax rate and the loan's interest rate and term.
- Select Calculate to see the monthly payment, total interest and full cost.
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Frequently asked questions
How is an auto loan payment calculated?
It uses the same amortisation formula as other loans: the amount financed is spread over the term at the monthly interest rate, so each payment covers interest first and then principal.
Is sales tax included in the amount financed?
In this calculator, sales tax is estimated on the vehicle price minus your trade-in value, and added to the amount you finance unless your down payment covers it. Tax rules vary by state.
Does a trade-in reduce my sales tax?
In many US states, yes — tax is charged on the price after the trade-in allowance. Some states tax the full price. Check your state's rule for an exact figure.