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Auto Loan Calculator

Monthly Payment: $659.38
Loan Amount: $33,300.00
Total Interest: $6,262.79
Total Cost (payments): $39,562.79
Vehicle True Cost (price + tax + fees): $38,300.00
Vehicle Price: $35,000.00 Trade-In Value: - $0.00 Taxable Amount: $35,000.00 Sales Tax (8.0%): + $2,800.00 Dealer Fees: + $500.00 ───────────────────── True Vehicle Cost: $38,300.00 Down Payment: - $5,000.00 Trade-In Credit: - $0.00 ───────────────────── Loan Amount: $33,300.00 Monthly Payment Formula: M = P × [r(1+r)^n] / [(1+r)^n - 1] P = $33,300.00 (loan principal) r = 7% / 12 = 0.005833 (monthly rate) n = 60 months Monthly Payment: $659.38 Total Paid (60 months): $39,562.79 Total Interest: $6,262.79
Amortization Summary (by Year)
YearPrincipal PaidInterest PaidRemaining Balance
1$5,764.16$2,148.40$27,535.84
2$6,180.85$1,731.71$21,354.98
3$6,627.67$1,284.89$14,727.32
4$7,106.78$805.78$7,620.53
5$7,620.53$292.03$0.00
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How to Calculate a Car Payment

An auto loan payment is calculated using the standard amortizing loan formula, the same used for mortgages. Each monthly payment covers the interest that accrued on the remaining balance plus a portion of the principal, structured so the loan reaches exactly $0 at the end of the term.

The key variables are the loan amount (principal), the annual interest rate, and the loan term in months. Your loan amount equals the vehicle price minus your down payment and trade-in, plus sales tax, dealer fees, and any other financed charges.

Auto Loan Payment Formula

The monthly payment formula for an amortizing loan:

M = P × [r(1 + r)n] / [(1 + r)n − 1]

VariableMeaningExample
MMonthly payment$594.04
PLoan principal$30,300
rMonthly interest rate (annual rate / 12)7% / 12 = 0.5833%
nTotal number of payments (months)60

Worked Example

You buy a car priced at $35,000, put $5,000 down, have no trade-in, 8% sales tax, a 60-month loan at 7% APR, and $500 in dealer fees.

Vehicle Price: $35,000 Sales Tax (8%): $35,000 × 8% = $2,800 Dealer Fees: $500 ───────────────── True Vehicle Cost: $38,300 Down Payment: - $5,000 ───────────────── Loan Amount (P): $33,300 Monthly Rate (r): 7% / 12 = 0.58333% Number of Payments (n): 60 months M = $33,300 × [0.005833 × (1.005833)^60] / [(1.005833)^60 - 1] M = $33,300 × [0.005833 × 1.4176] / [1.4176 - 1] M = $33,300 × [0.008269] / [0.4176] M = $33,300 × 0.019800 M = $659.54/month Total Paid: 60 × $659.54 = $39,572 Total Interest: $39,572 - $33,300 = $6,272

How Loan Term Affects Your Payment

Comparing a $30,000 loan at 7% interest across different terms:

Term Monthly Payment Total Interest Total Paid
24 months$1,344$2,253$32,253
36 months$927$3,360$33,360
48 months$718$4,494$34,494
60 months$594$5,640$35,640
72 months$512$6,840$36,840
84 months$453$8,034$38,034

Going from 60 to 84 months saves $141/month but costs an extra $2,394 in total interest. More importantly, a 7-year loan on a depreciating asset means you may be paying for a car that has already needed significant repairs — and you will likely be upside-down (owing more than the car is worth) for most of the loan period.

Understanding Auto Loan Costs

The true cost of car ownership extends beyond the sticker price and monthly payment. A $35,000 car with typical costs:

Sales tax is almost always financed into the loan because buyers rarely have extra cash on hand beyond the down payment. The $500 dealer fee used in this calculator is conservative — many dealers charge $700 or more. Always negotiate fees or ask for an itemized breakdown of all charges before signing.

Frequently Asked Questions

What is a good interest rate for an auto loan in 2025?

Average new car loan rates in 2025 range from about 5.5% to 8% for buyers with good credit (700+ score), and 9% to 15%+ for subprime borrowers. Credit unions typically offer rates 1–2% below banks. The best rates (under 5%) are often promotional financing from manufacturers. Your rate depends heavily on your credit score, loan term, and whether the vehicle is new or used — used car loans average about 2% higher than new car loans.

How much should I put down on a car?

A common rule of thumb is 20% down on a new car and 10% on a used car. A larger down payment reduces your monthly payment, lowers the total interest paid, and helps you avoid being "underwater" (owing more than the car is worth). Cars depreciate 15–25% in the first year, so without a meaningful down payment, you may owe more than the car is worth almost immediately. Even if you have a trade-in covering the down payment, make sure the net value is at least 10% of the vehicle price.

Does sales tax get added to the loan amount?

Yes, in most cases sales tax is financed as part of the auto loan. Most dealerships roll the sales tax, registration fees, and dealer fees into the loan. Our calculator assumes sales tax is charged on the vehicle price minus trade-in value (as most states do) and is added to the loan balance. Some states tax the full vehicle price regardless of trade-in. Always confirm the exact treatment with your dealership or state DMV.

What is the best loan term for a car?

Shorter loan terms (24–48 months) cost less in total interest and keep you from being underwater, but have higher monthly payments. Longer terms (72–84 months) have lower monthly payments but significantly more total interest — and a 7-year loan on a car that might need major repairs at year 5 or 6 is a financial risk. Most financial advisors recommend keeping car loans to 60 months maximum, and buying a car whose payment is no more than 10–15% of your monthly take-home pay.

How does a trade-in affect my auto loan?

Your trade-in value reduces the amount you need to finance. If your trade-in is worth $8,000 and you owe nothing on it, that $8,000 comes directly off the loan amount. If you still owe money on the trade-in (negative equity), that remaining balance is added to your new loan — a risky practice sometimes called "rolling over" debt. In most states, the trade-in also reduces the amount subject to sales tax: you pay tax on (vehicle price minus trade-in), not the full price.

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