How this car loan calculator works
A fixed-rate auto loan is paid off in equal monthly installments through a process called amortization. Each payment covers the interest due that month plus a slice of the remaining balance (the principal). Early on, more of the payment is interest; later, more of it goes to principal, but the monthly amount stays the same.
First the tool works out the amount financed: it takes the vehicle price, adds any sales tax (the price times your tax rate), then subtracts your down payment and trade-in value. That figure is P. The monthly payment then comes from the standard formula M = P · i · (1+i)n / ((1+i)n − 1), where i is the monthly interest rate — the APR divided by 12 — and n is the number of monthly payments (the term in months). When the APR is zero, the formula simplifies to M = P / n.
Total interest is the sum of all payments minus the amount financed, and total cost adds your down payment and trade-in back in to show the full out-of-pocket amount for the vehicle, taxes and financing combined.
Reference note: results are estimates and use a fixed rate for the whole term. They do not include dealer fees, registration, add-ons, extended warranties, gap insurance or rate changes, and currency is shown in US dollars. Tax handling varies by location — some areas tax the price after a trade-in credit. This is general math, not a loan offer or financial advice.
Frequently asked questions
- How is a car payment calculated?
- The monthly payment uses the amortization formula M = P · i · (1+i)^n / ((1+i)^n − 1), where P is the amount financed (price + tax − down payment − trade-in), i is the monthly rate (APR ÷ 12) and n is the number of months. If the APR is zero, the payment is simply P ÷ n.
- What APR is good on an auto loan?
- A lower APR means less interest over the life of the loan. The rate you are offered depends on your credit, the lender, the term and whether the car is new or used. There is no single universal number — compare offers from several lenders. This is general information, not a rate quote.
- How does the loan term affect total cost?
- A longer term (e.g. 72 months) spreads the loan over more payments, so each one is lower but you pay more total interest. A shorter term (e.g. 36 months) has higher monthly payments but less total interest, because the balance is paid off faster.
- Should I put money down on a car?
- A larger down payment, plus any trade-in value, reduces the amount you finance, lowering both the monthly payment and the total interest. It can also reduce the chance of owing more than the car is worth. The right amount depends on your situation — this is general information, not advice.
- Does this calculator include sales tax?
- It can. Enter an optional sales tax rate and the tool applies it to the vehicle price, then adds that tax to the amount financed. Leave it blank to ignore tax. Rules vary by location, so treat the result as an estimate.
- Is this an offer, and is it accurate?
- No. This is a neutral math tool, not a loan offer, quote or financial advice. Results are estimates and exclude items like fees, add-ons and dealer charges. Confirm real figures with a qualified professional or lender before deciding.