Car Loan Calculator: The Three Numbers That Matter
Every car loan comes down to price, rate, and term. Here is how each one moves your payment and your total cost.
A car loan's monthly payment is set by three inputs: the financed amount (price minus down payment and trade-in), the APR, and the term in months. Financing $30,000 at 7 percent for 60 months costs about $594 a month and $5,640 in total interest; the same loan at 4 percent costs about $552 a month and $3,140 in interest.
The financed amount
The financed amount is the vehicle price minus your down payment minus your trade-in equity, plus anything rolled in: sales tax, fees, warranties, or negative equity from a previous loan. Every dollar rolled in is a dollar you pay interest on for the whole term.
This is why negotiating the out-the-door price matters more than negotiating the monthly payment. Dealers can hit any monthly payment target by stretching the term; only the financed amount and the APR determine what the car really costs.
How APR moves the payment
On a $30,000 loan for 60 months, 4 percent APR gives a payment of about $552 and total interest of about $3,140. At 7 percent, the payment is about $594 with $5,640 in interest. At 10 percent, it is about $637 a month with $8,220 in interest.
A six-point rate swing costs nearly $5,000 on this loan. That is why the single highest-value move in car buying is lining up financing before you shop: a bank or credit union pre-approval gives you a rate to beat, and dealers routinely beat it or match it when they know you can walk.
How term moves the cost
Longer terms cut the payment and raise the total cost. That $30,000 at 7 percent: 36 months is about $926 a month with $3,330 in interest; 60 months is about $594 with $5,640; 72 months is about $511 with $6,790; 84 months is about $453 with $8,050 in interest.
The hidden cost of long terms is depreciation risk. Cars lose value fastest in the first two to three years, so a 72- or 84-month loan can leave you owing more than the car is worth for years. If the car were totaled, gap insurance covers the difference, but owing more than the asset is worth is a fragile position regardless.
The out-the-door checklist
Before signing, confirm five numbers in writing: the vehicle price, the trade-in value and any payoff, the APR (not just the payment), the term in months, and the total of payments. If any of them is missing or vague, stop and ask.
Decline or scrutinize add-ons in the finance office: extended warranties, paint protection, VIN etching, and similar products are high-margin and often cheaper elsewhere. Each $1,000 add-on at 7 percent over 60 months costs about $1,177 by payoff.
Skip the arithmetic
Run your own numbers through the free auto loan calculator before you visit the dealer.
Car loan questions
How do I calculate my car payment?
Use the amortization formula: the monthly payment equals the financed amount times the monthly rate, divided by one minus (1 + monthly rate) raised to the negative number of months. For example, $30,000 financed at 7 percent APR for 60 months gives a monthly payment of about $594.
What is the total cost of a car loan?
Multiply the monthly payment by the number of months to get the total of payments, then subtract the financed amount to find total interest. A $594 monthly payment for 60 months totals $35,640; on a $30,000 loan, that means $5,640 in interest.
Is 0% APR financing a good deal?
Often, but compare it against any cash rebate you forfeit by taking the promotional rate. A $3,000 rebate combined with a low bank or credit union rate can produce a lower total cost than 0 percent financing at full price. Run both scenarios through the calculator and compare total of payments.