How to Calculate Your Car Payment (Step-by-Step)
When you finance a car, your monthly payment isn't just the price of the car divided by the number of months. It's driven by three numbers: the amount you finance, your interest rate (APR), and your loan term. Change any one of them and your payment — and the total you'll pay — shifts dramatically.
Here's how the math works, and how to run it for your own purchase.
The 3 Numbers That Set Your Car Payment
- Amount financed — The car's price minus your down payment (and trade-in). This is what you actually borrow.
- APR — The annual percentage rate. A higher APR means more of each payment goes to interest.
- Loan term — How many months you take to repay. Longer terms lower the monthly payment but raise the total interest.
The Car Payment Formula
The standard auto-loan formula (the same one lenders use) is:
M = P × [ r(1 + r)ⁿ ] ÷ [ (1 + r)ⁿ − 1 ]
Where:
- M = your monthly payment
- P = the amount financed
- r = monthly interest rate (APR ÷ 12)
- n = total number of payments (years × 12)
You don't need to solve this by hand — the point is to understand that your payment is not linear. Cutting the term from 72 to 60 months raises the payment by only a little, but it saves a lot of interest.
A Real Example: $30,000 Car, 10% Down, 6% APR
| Item | Value |
|---|---|
| Car price | $30,000 |
| Down payment (10%) | $3,000 |
| Amount financed | $27,000 |
| APR | 6% |
| Term | 60 months (5 years) |
Monthly payment = $522
Over 5 years you'll pay about $31,319 total, including roughly $4,319 in interest.
💡 Try it yourself: Use our free auto loan calculator to enter your own numbers and see your exact payment and total interest.
How the Term Changes Your Payment
Same $27,000 loan, same 6% APR — different terms:
| Term | Monthly payment | Total interest |
|---|---|---|
| 36 months (3 yr) | $821 | $2,570 |
| 48 months (4 yr) | $634 | $3,437 |
| 60 months (5 yr) | $522 | $4,319 |
| 72 months (6 yr) | $447 | $5,218 |
| 84 months (7 yr) | $394 | $6,132 |
Notice the trade-off: the 7-year loan is almost $427 cheaper per month than the 3-year loan, but it costs about $3,562 more in interest.
Frequently Asked Questions
How is a car payment calculated?
It uses the amortization formula above: the amount financed, the monthly interest rate, and the number of payments. Your total cost is the monthly payment times the number of months.
What credit score gets the best car loan rate?
Generally 720 or higher unlocks the lowest APRs. Below 660, rates climb quickly because lenders see more risk.
Does my down payment lower my monthly payment?
Yes — every dollar down reduces the amount you finance, which lowers both your monthly payment and your total interest.
Is a longer loan term a good idea?
Only if you need the lower payment to fit your budget. A longer term always means more total interest, so choose the shortest term you can comfortably afford.
Ready to see your own numbers? Open the RateLedger auto loan calculator and get a full payment breakdown in seconds.