Auto Loan Calculator
An auto loan calculator estimates how much a car loan may cost before you apply. Enter the vehicle price, your down payment, the annual interest rate, the loan term, the sales tax rate, and upfront fees to see the financed amount, estimated monthly payment, total interest, total paid, and sales tax built into the deal. That gives you a faster way to compare a lower-priced car with a higher rate against a more expensive car with a stronger down payment or shorter term. Planning with an auto loan calculator is useful because small changes can move the payment more than many buyers expect. A longer term can reduce the monthly payment while raising the total interest. A bigger down payment can reduce both the balance and the interest paid over time. Taxes and fees matter too, since they often get rolled into the amount financed instead of being paid in cash at signing.
Quick answer
The calculator starts with vehicle price, subtracts the down payment, adds sales tax on the vehicle price, and then adds fees to estimate the amount financed.
What this tells you
- •The calculator starts with vehicle price, subtracts the down payment, adds sales tax on the vehicle price, and then adds fees to estimate the amount financed.
- •It converts the APR into a monthly rate and applies a standard amortization formula across the full term in months.
- •If the APR is 0%, the math becomes a simple division of the financed amount by the number of monthly payments.
- •Shorter terms usually raise the monthly payment but lower total interest because the balance is repaid faster.
- •Longer terms may look easier on a monthly budget, but they can add thousands of dollars in extra interest over the life of the loan.
How to Use
- 11. Enter the vehicle price before subtracting your down payment. Use the agreed purchase price for the car, truck, or SUV you plan to finance.
- 22. Enter the down payment you expect to pay upfront. If you are not sure yet, try a few amounts to see how each one changes the loan amount and payment.
- 33. Add the annual interest rate and the loan term in years. The tool converts years to monthly payments, so 5 years becomes 60 payments and 7 years becomes 84 payments.
- 44. Enter the estimated sales tax rate and any fees you expect to finance, such as documentation fees, title-related costs, or other dealer charges included in the loan.
- 55. Review the estimated loan amount, monthly payment, total interest, total paid, and sales tax. Compare multiple scenarios before shopping so you know what fits your payment target and total borrowing cost.
How It Works
Formula
Sales tax = vehicle price x tax rate
Loan amount = vehicle price - down payment + sales tax + fees
Monthly rate r = APR / 100 / 12
Monthly payment = P x [r(1+r)^n] / [(1+r)^n - 1]
If APR = 0, monthly payment = loan amount / nThis auto loan calculator uses the same structure lenders use for a fixed-rate amortizing loan. First, it calculates sales tax from the vehicle price and tax rate. Next, it estimates the principal balance by subtracting the down payment and adding sales tax plus financed fees. That financed balance is the starting loan amount shown in the results. For interest-bearing loans, P is the financed amount, r is the monthly interest rate, and n is the total number of monthly payments. The formula spreads repayment across equal monthly installments so each payment covers some interest and some principal. When APR is 0%, the calculator skips the amortization formula and simply divides the financed amount by the number of months. The tool assumes a fixed APR for the full term, monthly payments made on schedule, and no extra principal payments.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
New sedan with a moderate down payment
Sales tax is $2,450.00, so the financed amount becomes $35,000 - $5,000 + $2,450 + $1,200 = $33,650.00. Using a 6.5% APR over 60 months produces an estimated monthly payment of $658.40. This is a helpful baseline example because it shows how taxes and fees can push the financed balance above the simple price minus down payment math many buyers use at first glance.
Used SUV with a shorter term
The sales tax is $1,375.00 and the estimated amount financed is $21,025.00 after the down payment and fees. At 8.25% for 48 months, the payment is about $515.75 per month. Compared with stretching the same purchase over more years, this shorter term keeps total interest lower even though the monthly payment stays fairly high.
Higher-priced truck paid off in 3 years
Sales tax adds $4,080.00, which brings the financed amount to $41,880.00 after the $12,000 down payment and $1,800 in fees. The 36-month term creates a much higher monthly payment than a 60-month loan would, but total interest stays relatively contained at $3,238.86. This kind of example shows the tradeoff between cash flow now and lower borrowing cost later.
Zero percent promotional financing
This scenario uses the 0% APR path, so the financed amount is divided by 48 months instead of using the amortization formula. The amount financed is $25,840.00, made from $28,000 - $4,000 + $1,540 in tax + $300 in fees. Because the displayed payment is rounded to cents, multiplying $538.33 by 48 does not exactly reproduce the unrounded math behind the total, but the calculator correctly reports $25,840.00 paid in all.
Long 7-year term to lower the payment
The payment lands near the first example even though the vehicle price is higher, mainly because the term is stretched to 84 months. That lower monthly payment comes with a cost, since total interest climbs to $12,769.85. This is the kind of comparison that helps shoppers avoid choosing a longer term based only on the monthly number.
Nurse trading in a sedan for a used SUV
Priya, an ER nurse, is buying a three-year-old SUV for $27,500 and trading in a sedan the dealer values at $9,000 with $5,000 still owed, which leaves $4,000 in equity. Added to $2,000 cash, that makes the $6,000 down payment. Sales tax at 6.5% adds $1,787.50 and the $450 documentation fee is financed, so the loan is $27,500 - $6,000 + $1,787.50 + $450 = $23,737.50. At 7.49% over 60 months the payment is $475.54. Priya also ran 72 months and saw the payment fall to $410.31 while total interest rose to $5,804.76, so the shorter term won.
Monthly payment per $10,000 borrowed by APR and term
Find your APR row, read across to your term, and multiply by the number of $10,000 units you plan to finance. A $23,700 loan is 2.37 units, so at 7% for 60 months the payment is about 2.37 x $198.01, or roughly $469.
| APR | 48 months | 60 months | 72 months | 84 months |
|---|---|---|---|---|
| 3% | $221.34 | $179.69 | $151.94 | $132.13 |
| 4% | $225.79 | $184.17 | $156.45 | $136.69 |
| 5% | $230.29 | $188.71 | $161.05 | $141.34 |
| 6% | $234.85 | $193.33 | $165.73 | $146.09 |
| 7% | $239.46 | $198.01 | $170.49 | $150.93 |
| 8% | $244.13 | $202.76 | $175.33 | $155.86 |
| 9% | $248.85 | $207.58 | $180.26 | $160.89 |
| 10% | $253.63 | $212.47 | $185.26 | $166.01 |
| 11% | $258.46 | $217.42 | $190.34 | $171.22 |
| 12% | $263.34 | $222.44 | $195.50 | $176.53 |
| 13% | $268.27 | $227.53 | $200.74 | $181.92 |
Computed with the amortization formula above on a $10,000 balance with no tax or fees. The APR is the rate a lender must disclose under the Truth in Lending Act, Regulation Z (12 CFR 1026.18(e)), so look up that figure here rather than a dealer buy rate or a payment-only quote.
How term, down payment, trade-in, and negative equity change the cost
Stretching the term is the fastest way to lower the payment and the surest way to raise the total cost. On the $23,737.50 loan in the nurse example above, moving from 60 to 72 months drops the payment from $475.54 to $410.31 but lifts total interest from $4,794.78 to $5,804.76. The table shows the same pattern per $10,000. At 7% APR, 84 months costs $150.93 a month against $198.01 for 60 months, and you make 24 more of those payments.
A bigger down payment cuts the amount financed dollar for dollar, and every dollar you do not borrow never accrues interest. Regulation Z defines a downpayment to include the value of a trade-in (12 CFR 1026.2(a)(18)), so enter cash and trade-in equity together in the down payment field. Trade-in equity is the dealer's allowance for your old vehicle minus any loan balance still owed on it. In the example, $2,000 cash plus $4,000 of equity trims the payment by $80.13 a month compared with $2,000 alone and saves $807.97 in interest over the 60 months. Many states also charge sales tax only on the price after the trade-in allowance, while this calculator taxes the full price, so the tax line can run a little high in those states.
Negative equity flips that math. If you owe $14,000 on a vehicle the dealer values at $11,000, the $3,000 shortfall usually gets added to the new loan instead of reducing it. Model that here by putting the shortfall in the fees field, which the calculator adds to the financed balance. Rolling old debt into a new loan means paying interest on it a second time, and it starts the new loan with a balance above the vehicle's value, which is the situation GAP coverage exists for.
Two gaps in the model deserve a check before signing. First, the retail installment contract can carry items outside these inputs, such as dealer document fees you did not enter, title and registration, GAP coverage, service contracts, and other add-ons. Regulation Z requires the contract to show the amount financed, the finance charge, and the APR (12 CFR 1026.18), so compare those three lines with your estimate rather than the payment alone. Second, many auto loans accrue interest daily on a simple-interest basis, while this calculator applies one monthly rate on a fixed schedule, so paying early or late shifts how much of each payment goes to interest and the real totals drift a few dollars from the estimate.
Common mistakes
- Leaving out sales tax or financed fees, which makes the loan amount look smaller than the contract amount.
- Comparing two cars only by monthly payment instead of comparing monthly payment, total interest, and total paid together.
- Using the sticker price when you already negotiated a lower selling price, which can overstate the payment estimate.
- Treating a long loan term as automatically affordable without checking how much extra interest it adds over time.
- Assuming a prequalification rate, dealer ad, or promotional headline will match the final APR after credit review and lender conditions.
Limitations
This estimate assumes a fixed APR, equal monthly payments made on schedule, and no extra principal payments. It taxes the full vehicle price and then adds financed fees, which can differ from a state that credits the trade-in against the taxable price or a deal where tax and fees are paid in cash. The model ignores dealer document fees you did not enter, title and registration, GAP coverage, service contracts and other add-ons, rebates, negative equity from a trade-in, late fees, biweekly schedules, and refinancing later. Regulation Z requires the retail installment contract to disclose the amount financed, the finance charge, and the APR (12 CFR 1026.18), and it treats a disclosed APR as accurate if it is within one-eighth of one percentage point of the actual rate on a regular transaction (12 CFR 1026.22(a)(2)), so a small gap between this estimate and the contract is normal. Many auto loans also accrue interest daily on a simple-interest basis rather than once a month, which moves the totals a little when payments arrive early or late. Use the result to compare scenarios, not to predict the exact figures on your contract.
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