Methodology

How the calculators work

All five calculators run in your browser. Nothing you type is sent to us unless you choose to send a financing request afterward. Their results are estimates, not offers: a lender’s actual payment can differ by a few cents or more because of its own rounding, the date of the first payment, fees and taxes.

The calculators follow the conventions of a simple-interest installment contract, the usual form of a US car loan:

• The APR is applied monthly: the monthly rate r is the APR divided by 12.
• The level monthly payment for an amount financed P over n months is P × r ÷ (1 − (1 + r)^−n), rounded to the cent. At 0% APR it is simply P ÷ n.
• Each month, interest is the remaining balance times r, rounded to the cent. The rest of the payment reduces the balance.
• The last payment clears whatever is left, so it can differ from the others by a few cents.

Example: $25,000 at 7% APR for 60 months gives a payment of $495.03. Over the 60 months you pay $4,701.82 in interest, $29,701.82 in all.

Car payment calculator

Takes the price, down payment, APR and term, works out the amount you would finance, and applies the formula above. It shows the monthly payment, the total interest over the loan and the total cost.

Affordability calculator

Works backward from a monthly budget. First it finds the loan amount that budget repays at your APR and term: budget × (1 − (1 + r)^−n) ÷ r. It adds your cash down payment and trade-in equity to get the most you could spend out the door. It then subtracts fees and divides by 1 plus the sales tax rate to estimate the vehicle price that fits. A budget of $495.03 a month at 7% for 60 months, for example, repays a loan of about $25,000.

Auto refinance calculator

Compares your current loan (balance, APR, months left) with a new loan at a new APR and term. Refinance fees can be paid in cash or rolled into the new balance. It shows:

• the current and new monthly payments and the difference;
• the interest still ahead on the current loan and the interest on the new loan;
• net savings: everything left to pay on the current loan, minus everything you would pay on the new loan, minus fees paid in cash;
• break-even months: total fees divided by the monthly payment drop, rounded up. If the payment does not fall, there is no break-even point.

A refinance that trims the monthly bill by adding months may still cost you more overall, which is why the calculator shows both figures.

Out-the-door price calculator

Adds up what a car costs before financing and what is left to borrow:

1. Taxable amount: price plus the dealer’s documentation fee plus taxed add-ons (service contracts, GAP and similar). Where your state taxes only the difference, the trade-in value is subtracted first.
2. Sales tax: the taxable amount times your tax rate.
3. Out-the-door price: price, doc fee and add-ons, plus tax, plus title, registration and other government fees.
4. Amount financed: out-the-door price minus trade-in equity (trade-in value minus what you still owe on it), minus any rebate and cash down. Negative equity, when you owe more than the trade-in is worth, is added to the amount financed.

Tax rules for trade-ins, rebates and add-ons vary by state; our state laws pages describe them where state law does.

Loan term comparison

Shows the same amount financed at one APR over terms from 36 to 84 months: the payment, total interest, total paid, and the share of the original amount still owed after 36 payments. For $25,000 at 7%, a 36-month loan costs $2,789.42 in interest and an 84-month loan $6,694.46; after 36 payments on the 84-month loan, about 63% of the original amount is still owed. Real offers often carry a higher APR for longer terms, so the comparison understates the cost of stretching a loan.

Market rates and averages

Average rates by credit tier, average loan amounts, payments and terms in our articles come from:

• Experian, State of the Automotive Finance Market (commercial market data, published quarterly). We currently use the Q2 2026 report, which groups borrowers by VantageScore 4.0 bands. The credit bands on our financing request form follow the same ranges.
• Federal Reserve G.19 Consumer Credit release. We use the release of October 7, 2026, with Q2 2026 figures for commercial bank new-car rates on 60- and 72-month loans and for finance company rates, terms and amounts.

When a newer quarter is published, we update the figures and the dates on the pages that use them.

How state pages are researched

Each page in our state laws section is built from the state’s statutes, its financial regulator and its revenue department, opened directly. For every state we look at the same points: whether borrowers have a right to cure (to keep the car by paying only the missed payments and allowed costs, either after a warning notice or by reinstating the loan after a repossession; a right to buy the car back by paying the whole balance does not count), the rate ceiling for dealer-arranged contracts, any limit on documentation fees, the rules after repossession, the vehicle sales tax and trade-in credit, and the regulator that licenses sales finance companies.

Every state page lists its sources and the date they were checked. Where a statute is ambiguous or applies only to some lenders, the page explains the limit rather than simplifying it away. Changes are logged on our updates page, and our editorial policy describes the review process.