Auto Loan Calculator

How the Auto Loan Calculator works

Use this calculator when you want a mechanical estimate from vehicle price, down payment, trade-in value, entered annual rate, and term months. Use Loan Payment for a generic fixed-rate loan, APR when fees need an APR-style cash-flow estimate, Payment or Amortization for broader payment and schedule questions, Cash Back or Low Interest for two vehicle-incentive offers, Lease for lease assumptions, and Debt-to-Income or Budget for monthly pressure. Use CFPB auto-loan materials, Regulation Z, FTC dealer-advertising and financing guidance, lender disclosures, state DMV or tax authorities, and legal sources for real APR, Truth in Lending disclosures, taxes, registration, rebates, add-ons, eligibility, approval, or jurisdiction-specific claims.

Financed amount is max(0, vehiclePrice - downPayment - tradeInValue). Monthly rate is annualRate / 100 / 12. For a nonzero rate, monthly payment is P * r / (1 - (1 + r)^(-n)), where P is financed amount, r is monthly rate, and n is termMonths. For a zero rate, monthly payment is financedAmount / termMonths. Total paid is monthly payment times termMonths, and total interest is total paid minus financed amount. Total paid excludes the down payment, trade-in value, sales tax, registration, dealer fees, insurance, rebates, and any payoff or negative-equity amount on a trade-in.

Auto Loan Calculator formula

This formula page covers the app's Auto Loan Calculator: a fixed-rate vehicle-loan estimate from vehicle price, down payment, trade-in value, annual rate, and term in months. It estimates financed amount, monthly payment, total paid, and total interest before sales tax, title, registration, dealer fees, rebates, insurance, maintenance, negative equity, lender underwriting, or legal lending disclosures.

Step by step

1. Read vehicle price, down payment, trade-in value, annual rate, and term in months from the calculator inputs.
2. Subtract down payment and trade-in value from vehicle price.
3. Apply the app's safety floor with P = max(0, Price - Down - Trade), so over-offset inputs do not create a negative loan balance.
4. Convert the entered annual percentage rate into a decimal annual rate by dividing by 100.
5. Convert the decimal annual rate into the app's monthly rate assumption by dividing by 12.
6. If the monthly rate is 0, divide the financed amount by the term in months to get the level monthly payment.
7. Otherwise, solve the fixed amortizing payment with P times m divided by 1 minus (1 + m) raised to negative n.
8. Calculate total paid as monthly payment times term months.
9. Calculate total interest as total paid minus the financed amount.
10. Round displayed currency outputs to two decimals after the full-precision calculation.
11. Treat APR, finance charge, amount financed, total-of-payments disclosure, Truth in Lending, taxes, title, registration, rebates, negative equity, add-ons, lender underwriting, dealer claims, and local legal rules as separate topics that need CFPB, Regulation Z, FTC, lender, dealer, state DMV, tax-authority, regulator, or legal source checks.

Worked example

Default example: $35,000 vehicle, $5,000 down, $3,000 trade, 7 percent, 60 months

The default calculator inputs use a $35,000 vehicle price, a $5,000 down payment, a $3,000 trade-in value, a 7 percent annual rate, and a 60-month term.

1. Subtract the $5,000 down payment and $3,000 trade-in value from the $35,000 vehicle price.
2. The financed amount is $27,000 because $35,000 - $5,000 - $3,000 = $27,000.
3. Convert 7 percent to the decimal annual rate 0.07.
4. Divide 0.07 by 12 to get a monthly rate of about 0.0058333.
5. Use n = 60 monthly payments.
6. Apply PMT = P * m / (1 - (1 + m)^-n) with P = $27,000, m about 0.0058333, and n = 60.
7. The calculator reports a monthly payment of $534.63.
8. Total paid is the full-precision monthly payment times 60, reported as $32,077.94.
9. Total interest is total paid minus the $27,000 financed amount, reported as $5,077.94.
10. The zero-rate fixture uses a $22,000 vehicle, $3,000 down, $1,000 trade-in value, 0 percent, and 36 months. It finances $18,000, divides by 36, and reports a $500 monthly payment, $18,000 total paid, and $0 interest.

The formula can help compare how purchase price, down payment, trade-in value, rate, and term change the mechanical loan estimate. It does not show a lender quote, dealer out-the-door price, approval, legal disclosure, or personalised vehicle-financing recommendation.

Assumptions and what this calculator ignores

Geographic scope: works globally. The math is currency-agnostic, so enter amounts in your own currency; local taxes, fees, and product rules are not included.

• The calculation models one fixed-rate vehicle loan with equal monthly payments. The entered term in months is the payment count, and the entered annual rate is converted to a simplified monthly rate.
• Vehicle price, down payment, and trade-in value are simple offsets. The trade-in field is not a payoff amount, negative-equity amount, tax-credit rule, dealer appraisal, or guarantee that the trade-in value will be available. If down payment plus trade-in exceed vehicle price, the financed amount is floored at zero.
• The calculator excludes sales tax, title, registration, documentation fees, dealer add-ons, optional credit insurance, GAP, rebates, maintenance, insurance, variable rates, prepayment rules, late fees, credit approval, and legal disclosures. Scoped independent comparator checks pass for overlapping fixed-payment and zero-rate outputs, while CFPB, Regulation Z, FTC, lender, state DMV, state tax, and legal sources are needed before making real APR, Truth in Lending, advertising, registration, tax, product-specific, eligibility, approval, or jurisdiction-specific claims. Results are educational estimates, not financial, legal, tax, lending, credit, consumer-rights, regulatory, or personalised advice.

What this formula does not include

• The calculator models one fixed-rate vehicle loan with level monthly payments. It does not model variable rates, promotional-rate changes, interest-only periods, balloon payments, deferred payments, late fees, prepayment penalties, or payment holidays.
• The annual rate input is divided by 12 for the payment formula and is not automatically a legal APR. APR, finance charge, amount financed, payment schedule, total of payments, and Truth in Lending copy need CFPB, Regulation Z, lender, or legal source checks.
• The financed amount floor at zero prevents negative payment bases when down payment plus trade-in value exceed vehicle price, but it does not model cash due back, equity refunds, dealer appraisal adjustments, trade payoff amounts, or negative equity.
• No sales tax, title, registration, documentation fee, dealer fee, origination charge, lien fee, destination charge, warranty, gap coverage, credit insurance, maintenance plan, rebate, manufacturer incentive, lender credit, or add-on product is included.
• No credit score, underwriting, approval odds, loan-to-value test, collateral valuation, income verification, debt-to-income review, lender contract, dealer contract, advertising rule, or jurisdiction-specific lending rule is modeled.
• The trade-in input is a simple positive offset. It does not decide whether a dealer will accept the trade, how payoff balance is handled, whether negative equity is rolled in, or whether the trade changes sales-tax treatment.
• The page is not an amortization schedule, payoff quote, lease comparison, cash-back-versus-low-interest analysis, title or tax lookup, insurance estimate, vehicle affordability test, or regulated consumer-credit disclosure.
• Package fixtures currently cover the default fixed-rate branch and the 0 percent zero-rate branch; use the independent comparator only as an overlapping-payment comparator because it can include sales tax, fees, trade-in state, negative-equity, and payoff fields this app omits.
• Use CFPB auto-loan terms and offer-comparison guidance, CFPB Truth-in-Lending disclosure materials, Regulation Z, FTC dealer-financing guidance, lender or dealer documents, state DMV and tax authorities, state regulators, or legal sources before making real APR, total-cost, tax, title, registration, rebate, add-on, approval, advertising, negative-equity, or jurisdiction-specific claims.
• The result is an educational estimate from the entered assumptions, not financial, tax, legal, lending, credit, consumer-rights, regulatory, vehicle-purchase, or personalised advice.

Common mistakes to avoid

• Reading the monthly payment as the full ownership cost. The calculator does not include taxes, title and registration fees, dealer add-ons, insurance, fuel, maintenance, repairs, parking, or depreciation.
• Treating the entered annual rate as the legal APR or a dealer quote. APR disclosures can include required fees and legal timing rules that this calculator does not model.
• Entering a trade-in payoff or negative-equity amount as if it were positive trade-in value, or reading Total paid as the total purchase cost. Total paid is only the modeled loan-payment stream after the simplified financed amount is calculated.

Key terms

Amount financed

The vehicle price left after subtracting the entered down payment and trade-in value. This calculator floors the amount at zero and then amortizes it over the selected months.

Monthly payment

The equal payment estimated for each month of the selected term. It uses the fixed-rate payment formula unless the entered annual rate is zero.

Entered annual rate

The percentage rate entered by the user for the simplified estimate. The calculator divides it by 100 and 12. It is not a legal APR disclosure or lender quote.

Frequently asked questions

Methodology, sources, and disclaimer

This calculator is an original vehicle-loan model netting down payment and trade-in from price before level-payment amortization over a term in months, validated by deterministic fixtures, edge cases, and rounding policy tests. It is not copied from a single source.

Fixtures pin the financed-amount netting and the 60-month default payment. The result remains an educational estimate, not a dealer quote or a loan approval.

Formula version 2026.05.20. The version marks the calculation logic and validation fixture set used for this estimate.

• CFPB auto-loan key terms and offer-comparison guidance should be used before copy defines APR, interest rate, loan term, down payment, trade-in, negative equity, amortization, total cost, or payment-shopping context.
• CFPB Truth-in-Lending auto-loan disclosure materials and Regulation Z sections 1026.18 and 1026.22 should be used before copy discusses legal APR, finance charge, amount financed, payment schedule, total of payments, disclosure accuracy, or creditor disclosure requirements.
• FTC financing-or-leasing guidance, lender or dealer documents, state DMV and tax authorities, state regulators, and legal sources should be used before copy makes product-specific, approval, tax, title, registration, rebate, add-on, advertising, negative-equity, or jurisdiction-specific claims.

Results are educational estimates, not advice. Read the full disclaimer.

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