Auto Loan Calculator: How Your Car Payment Is Computed
An auto loan calculator answers one question with a single number: what do you pay every month? Behind that number sit three inputs and one formula. The inputs are the amount financed, the annual percentage rate and the number of payments. The formula turns them into a payment that stays fixed for the life of the loan, while the mix of interest and principal inside that payment changes every month. The calculator on this page runs the arithmetic instantly and prints the month-by-month schedule a lender would hand you.
What goes into an auto loan calculator
The tool asks for three values, and it takes them in the units lenders quote. The loan amount is entered in dollars and it means the amount financed, not the sticker price. The annual interest rate is entered in percent with a step of 0.1, so an offer of 6.9% goes in as 6.9. The term is entered in years in half-year steps: 5 for a 60-month loan, 5.5 for 66 months. The field accepts values from 0.5 to 50 years, which covers every consumer auto loan in the market and leaves room to see what a very long term would cost.
The amount financed is where most of the thinking happens before any number reaches the calculator. It is not the price on the window sticker. Sales tax, title and registration fees, dealer documentation fees and any rolled-in add-ons increase it. A down payment, a manufacturer rebate and the trade-in allowance reduce it, and negative equity from a previous loan is added back. The calculator takes the net figure you give it and amortizes that amount.
The output is the monthly payment, the total paid across the term, the total interest, the principal-versus-interest split as a percentage, and the full month-by-month schedule. A 0% rate is treated as its own case: the amount financed is divided evenly across the months and total interest is zero.
The formula behind the payment
A fixed-rate auto loan is an amortizing loan. Every payment covers the interest due on the remaining balance, and whatever is left over reduces that balance. The payment that brings the balance to exactly zero in the final month is:
$$M = P \frac{r(1+r)^n}{(1+r)^n - 1}$$
M is the monthly payment, P is the amount financed, r is the monthly rate (the annual rate divided by 100, then by 12) and n is the number of payments. The same value comes from the equivalent form M = P × r / (1 − (1 + r)^−n), which some lenders print on their disclosures.
A worked example makes it concrete. Finance $32,000 at 6.9% over 60 months. The monthly rate is 6.9 / 100 / 12 = 0.00575. Raising 1.00575 to the 60th power gives 1.41060. The formula then reads:
$$M = \frac{32{,}000 \times 0.00575 \times 1.41060}{1.41060 - 1} = 632.13$$
The payment is $632.13. Across 60 months that is $37,927.78 in total payments, so the interest bill comes to $5,927.78, which is 18.5% of the amount borrowed.
Checking the result without trusting it
Running the formula once by hand is worth the minute it takes, because it separates the inputs that move a payment from the ones that do not. Hold the amount at $32,000 and the rate at 6.9%, and the arithmetic stays steady: each additional $1,000 financed adds about $19.75 a month on a 60-month term. Change the term instead and the payment moves a long way, which is the subject of the next section.
Where the money goes in a five-year loan
The payment never changes, but its composition does. Interest is charged on the outstanding balance, and the balance falls with every payment, so the interest portion shrinks and the principal portion grows.
| Month | Payment | Principal | Interest | Balance | Interest share |
|---|---|---|---|---|---|
| 1 | $632.13 | $448.13 | $184.00 | $31,551.87 | 29.1% |
| 12 | $632.13 | $477.30 | $154.83 | $26,449.08 | 24.5% |
| 24 | $632.13 | $511.30 | $120.83 | $20,502.79 | 19.1% |
| 36 | $632.13 | $547.72 | $84.41 | $14,132.98 | 13.4% |
| 48 | $632.13 | $586.73 | $45.40 | $7,309.49 | 7.2% |
| 60 | $632.13 | $628.52 | $3.61 | $0.00 | 0.6% |
Two details surprise most borrowers. The first is how little the balance moves at the start. After a $632.13 payment in month one, a $32,000 loan still owes $31,551.87, because $184.00 of that payment was the cost of borrowing. The second is that a five-year auto loan is already principal-heavy in month one, where $448.13 reduces the balance against $184.00 of interest. On a 30-year mortgage at a comparable rate the interest portion dominates for years, and the crossover arrives in the 2030s. The shorter the term, the sooner principal outruns interest.
The column that matters for planning is the balance. It marks the point where you owe less than the car is worth, and that is where selling or trading stops being a loss-making move.
What each extra year of term costs
Term is the input with the largest effect on both the payment and the total cost. Take the same $32,000 at 6.9% and spread it over the five standard auto loan lengths.
| Term | Monthly payment | Total interest | Total paid |
|---|---|---|---|
| 36 months | $986.60 | $3,517.77 | $35,517.77 |
| 48 months | $764.80 | $4,710.21 | $36,710.21 |
| 60 months | $632.13 | $5,927.78 | $37,927.78 |
| 72 months | $544.03 | $7,170.37 | $39,170.37 |
| 84 months | $481.40 | $8,437.85 | $40,437.85 |
Moving from 60 to 84 months cuts the payment by $150.73 a month and adds $2,510.07 to the interest bill. The lower payment is real, and so is the extra cost. The calculator shows both in the same view, so the trade is never hidden behind a comfortable monthly figure.
A longer term also flattens the balance curve. Principal is retired more slowly, and a new car typically loses about 20% of its value in the first year, so a 72- or 84-month loan can stay underwater for years. The average new car loan term in the United States has reached 69 months, and 72-month loans are the single most common choice at roughly 36% of originations. Financial planners still draw the line at 60 months or less, for the reason the table above shows.
Real auto loan rates by credit tier
The rate is set by your credit profile, the vehicle, the term and the lender. National averages by credit tier, from Experian's second-quarter 2026 data:
| Credit tier | New car APR | Used car APR |
|---|---|---|
| Superprime (781+) | 4.41% | 6.29% |
| Prime (661-780) | 6.15% | 8.81% |
| Nonprime (601-660) | 9.71% | 13.93% |
| Subprime (501-600) | 13.52% | 19.10% |
| Deep subprime (300-500) | 16.11% | 21.62% |
The distance between tiers is the strongest argument for knowing your own rate before you shop. On the same $32,000 over 60 months, the prime-tier average of 6.15% produces a payment of $620.88 and $5,253.04 in interest. The subprime average of 13.52% produces $736.64 a month and $12,198.69 in interest. Same car, same term, twice the interest cost, and the only variable is the rate.
A down payment of 20% on a new car and 10% on a used one is the conventional target, and it does more than lower the payment. It keeps the loan from starting underwater, which is what makes a long term risky in the first place.
Using the auto loan calculator step by step
Three steps, and the answer is on screen:
- Enter the amount you will finance, in dollars.
- Enter the annual rate the lender quoted, such as 6.9.
- Enter the term in years. Five years is 5, and a 66-month loan is 5.5.
The results appear immediately: monthly payment, total payment, total interest and the principal-to-interest split. Open the schedule to see every row, with the interest and principal portions and the remaining balance after each payment.
Two behaviors are worth knowing. At 0% the tool divides the amount evenly: $28,800 over 60 months gives $480.00 a month and no interest at all, which is the right comparison against a cash rebate on a promotional financing offer. And because the term field accepts half-years up to 50 years, a 66-, 75- or 84-month offer can be priced exactly as the dealer wrote it, with no rounding to the nearest year.
Every calculation runs in the browser, so the price, rate and salary figures you try stay on your own device.
Frequently Asked Questions
How is an auto loan monthly payment calculated?
The lender applies the amortizing-loan formula to the amount financed, the monthly rate and the number of payments. The payment is fixed for the term, and each installment splits between interest on the remaining balance and principal reduction. The calculator on this page does the same computation and shows every row of the resulting schedule.
What happens at a 0% interest rate?
The tool divides the amount financed evenly across the payments. A $28,800 loan over 60 months becomes $480.00 a month with no interest, and the balance falls by the same amount every month. It is the correct way to price a zero-percent promotional offer against a cash rebate.
Why is so much of my early payment interest?
Interest is charged on the outstanding balance, which is at its largest in the first month. As the balance falls, the interest charge falls with it. The payment itself does not change; only its split between interest and principal moves. On a five-year loan at 6.9%, the first payment is 29.1% interest and the final one is 0.6%.
How much does a longer term really cost?
On $32,000 at 6.9%, stretching from 60 to 84 months lowers the payment by $150.73 a month and raises the total interest from $5,927.78 to $8,437.85, a difference of $2,510.07. The payment gets easier and the loan gets more expensive, and both numbers come from the same calculation.
What APR should I expect with average credit?
Prime-tier borrowers, with scores from 661 to 780, saw an average of 6.15% on new cars and 8.81% on used cars in Experian's second-quarter 2026 data. Rates above and below that band follow credit score closely, which is why a pre-approval from your own bank or credit union is worth having before you talk to a dealer.
Can I use it for a used car or a refinance?
Yes. The math does not care what the money buys. For a refinance, enter the payoff balance as the amount financed, the new rate and the remaining term. For a used car, enter the amount after the down payment and any trade-in, and use the used-car rate from the table above.
The numbers to check before you sign
A car payment is the product of an amount, a rate and a term, and the term is the input that hides the most cost. The calculator makes that visible: enter the offer, then enter the same offer with a shorter term and a larger down payment, and compare the total interest rather than the monthly figure. A payment that fits a budget is not the same thing as a loan that is cheap.
Four figures are worth capturing before any signature: the amount financed (not the price), the rate, the term in months and the total interest. If the total interest on an 84-month offer is thousands of dollars above the 60-month figure on the same amount, the arithmetic is telling you that the price is the problem, not the financing. Run both scenarios through the calculator, keep the schedule, and walk in with the numbers already known.
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