Guide
How car loan APR changes your payment
APR is the number that turns a price into a payment. Two shoppers can buy the same car for the same money down over the same term and still owe different amounts each month, because their rates differ. This guide shows what APR is, how it enters the math, and what a rate difference is worth in dollars. Every figure below comes from the car payment calculator.
APR versus the monthly rate
APR stands for annual percentage rate. It expresses the yearly cost of borrowing as a percentage of the amount financed. Lenders quote APR annually because it makes offers of different sizes comparable.
The payment formula does not use the annual figure. It uses the monthly interest rate: the APR divided by 100, then divided by 12.
- A 6% APR is 6 ÷ 100 ÷ 12 = 0.005 per month.
- A 9% APR is 9 ÷ 100 ÷ 12 = 0.0075 per month.
That monthly rate is applied to the balance you still owe, so it shapes both the size of each payment and how much of it goes to interest instead of principal. The step-by-step math is in the guide to how car payments are calculated.
One caution on terminology: an APR can include certain finance charges alongside the interest rate, so a lender's APR and its quoted interest rate are not always the same number. This calculator treats the APR you enter as the rate behind the monthly figure.
Side by side
What a rate difference costs
Both columns below use the same $35,000.00 vehicle price, the same $5,000.00 down payment, and the same 60-month term, so the amount financed is $30,000.00 in each case. Only the APR changes. For the effect of moving that deposit instead, read the guide to car down payments.
| APR | Monthly payment | Total interest |
|---|---|---|
| 6% | $579.98 | $4,799.04 |
| 9% | $622.75 | $7,365.04 |
Three percentage points add $42.77 to the monthly payment and $2,566.00 to the interest paid over the full term. The car, the down payment, and the term never moved.
Why the total grows faster than the payment
The monthly payment rises about 7%, but the interest paid rises by more than half. Interest is only a slice of each payment; the rest repays the balance. A higher rate lands almost entirely on that slice, so it moves the borrowing cost far more, in proportion, than it moves the amount you hand over each month. A longer term widens the gap again, because the balance stays high for more months, as the guide to choosing a car loan term sets out.
Enter these values in the calculator to reproduce either column. Both differences are figured from unrounded payments, so multiplying the rounded $42.77 by the 60 payments lands about 20 cents away from $2,566.00 rather than exactly on it.
Why an advertised rate is not the rate you get
An advertised APR is a starting point for a conversation, not an offer that has been made to you. Seeing a rate published is not a guarantee that it will appear on your contract.
Lenders set the rate on an individual application, and the figure can move with credit history, the size of the down payment, the length of the term, the age and mileage of the vehicle, and whether the loan is new or a refinance. Promotional rates are often limited to shorter terms, specific models, or a narrow band of applicants, and a manufacturer's low-rate offer is sometimes an alternative to a cash rebate rather than an addition to it.
Because of that, treat any APR you type here as a scenario. Run the payment at the rate you hope for and again at a higher one, and see whether the higher figure still fits. The only rate that matters is the one written on the contract you sign.
Keep in mind
What this comparison leaves out
These figures are planning estimates, not loan offers. A lender works from the amount it actually finances and applies its own rounding, payment dates, and day-count conventions, so its quote can differ from any calculator.
The simple calculator also excludes sales tax, title and registration, dealer and documentation fees, insurance, fuel, and maintenance. When those amounts are financed they join the principal, which raises the monthly payment and the total interest at any APR.
Compare written offers on the same price, down payment, and term, and confirm the final figures with the seller and the lender before signing anything.