b2KIT

Auto / Car Loan Calculator

Calculate monthly car payments with trade-in value, down payment, taxes, and total cost of ownership.

Tested tool guide Tested browser tools Checked August 16, 2026

What Auto / Car Loan Calculator does, with a checked example

Price alone does not determine what a financed car costs each month. This calculator combines vehicle price, trade-in credit, cash down, sales tax, loan APR, and term to estimate the amount financed, monthly payment, interest, and entered ownership cost. It is useful for comparing deal structures before accepting a quote. The common surprise is that a smaller loan payment does not necessarily mean a cheaper car: a larger down payment or trade-in lowers the payment while shifting value outside the loan.

Worked example

A concrete input and expected output from the current implementation.

Input

Vehicle price: $12,000; trade-in value: $0; down payment: $0; sales tax: 0%; APR: 0%; loan term: 12 months

Expected output

Amount financed: $12,000. Monthly payment: $1,000. Total interest: $0. Total of 12 loan payments: $12,000. Total cost represented by these inputs: $12,000.

With no trade-in, down payment, or tax, the full $12,000 is financed. At 0% APR, dividing $12,000 by 12 produces exactly twelve $1,000 payments, so the payment total remains $12,000.

How the result is produced

1

Amount financed

The calculation begins with the vehicle price and the entered adjustments for trade-in value, down payment, and tax. Their combination determines the principal financed. Trade-in tax treatment is not uniform across jurisdictions, so a result based on a general tax entry may differ from a dealer worksheet that applies local rules.

2

Payment and cost totals

For a level-payment loan, the APR and selected term determine the scheduled monthly payment on the amount financed. Each payment combines interest and principal reduction. Total loan interest is the scheduled payment total minus financed principal. The ownership total covers only costs represented by the calculator's fields, not every possible expense of keeping the car.

Good uses

  • Compare 36-, 48-, and 60-month financing offers for the same vehicle price and APR.
  • Test how a proposed trade-in value or larger cash down payment changes the loan payment.
  • Estimate whether a specific new or used car fits a monthly budget after tax and financing.

Limits and checks

  • Sales-tax treatment of trade-ins and rebates varies by jurisdiction, so the calculator's taxable amount may not match the final contract.
  • Dealer fees, title charges, payment timing, and lender rounding can make an actual payment differ from the estimate.
  • Do not read the ownership total as including depreciation, insurance, fuel, maintenance, registration, or repairs unless those costs are explicitly entered.

Common questions

Does the monthly payment include insurance, fuel, and maintenance?

No. The loan payment is based on the amount financed, APR, and term. Insurance, fuel, maintenance, repairs, and similar running expenses are separate unless the calculator provides dedicated fields and you enter them. Add those expenses independently when deciding whether the car fits your full monthly budget.

Will the calculated payment match the dealer's payment exactly?

Not necessarily. It should match when the financed amount, APR, term, tax, and included charges match, subject to rounding. A dealer contract can also contain title costs, documentation charges, add-on products, or a different tax basis. Compare the calculator's amount financed with the contract before comparing monthly payments.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.

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