New Car Payment Calculator and Monthly Cost

This calculator estimates a level monthly payment for a new-car loan from the amount financed, annual percentage rate (APR), and loan term. Enter those three figures to see the estimated payment and total interest; the result excludes taxes, insurance, and other costs of owning a car.

Formula

The calculator uses the standard fixed-rate, fully amortizing loan payment formula:

Monthly payment = P × r ÷ [1 − (1 + r)⁻ⁿ]

• P is the amount financed, in dollars.
• r is the monthly interest rate, calculated as APR ÷ 1,200. APR is entered as a percentage per year, so an 8% APR gives a monthly rate of 8 ÷ 1,200.
• n is the number of monthly payments, calculated as the term in years × 12.

Total interest is estimated as the rounded monthly payment multiplied by the number of payments, minus the original amount financed: interest = payment × n − P. The payment is rounded to cents before the total is calculated.

Worked Example

Using the calculator’s defaults—$20,000 financed, 8% APR, and five years—the number of payments is 5 × 12 = 60, and the monthly rate is 8 ÷ 1,200 = 0.0066667.

Substitute those values into the payment formula:

$20,000 × 0.0066667 ÷ [1 − (1 + 0.0066667)⁻⁶⁰] = $405.53 per month

The total of the rounded payments is $405.53 × 60 = $24,331.80. Estimated interest is $24,331.80 − $20,000 = $4,331.80. These results assume the same payment and rate throughout the loan.

Assumptions

• The interest rate is fixed for the full term.
• Payments are equal monthly payments, made at the end of each monthly period.
• Interest compounds monthly using APR divided by 12.
• The calculation does not include fees, taxes, insurance, add-ons, or other amounts that may be included in a vehicle purchase or financing contract.

What Determines a New Car Payment?

The payment depends chiefly on the amount financed, APR, and term. The amount financed is not necessarily the car’s advertised price: it may reflect a down payment or trade-in, taxes and fees added to the loan, and any balance carried over from another loan. To estimate a payment accurately, use the amount the lender says will actually be financed rather than the vehicle’s sticker price.

A larger amount financed raises the payment when the APR and term stay the same. A higher APR also raises both the monthly payment and total interest. Extending the term usually lowers the scheduled monthly payment, but it means making more payments and can increase the total interest paid. The calculator isolates these effects; it does not determine the vehicle’s final transaction price or the terms a lender may offer.

How to Use the Estimate

Enter the principal, APR, and term from a written loan quote or adjust them to explore scenarios. For a useful estimate, check whether the quote’s amount financed includes items that you expect to finance, and whether its term is stated in years or months. This calculator takes years. For example, a 60-month term is entered as 5 years.

Compare estimates on the same basis: use the same amount financed and term when examining different APRs, or the same APR and amount when examining different terms. A lower monthly payment alone does not show the total cost of borrowing. Review both the payment and total interest, then check the lender’s itemized disclosures for fees and other contract details.

Payment Versus the Full Cost of a Car

A loan payment is only one part of the cost of owning and operating a car. Depending on the vehicle and the owner’s circumstances, the overall budget may also include insurance, fuel or electricity, maintenance, repairs, registration, parking, and taxes. Those expenses are not part of the formula and can vary independently of the loan payment.

Down payments and trade-ins can reduce the amount financed, but they do not change the loan’s APR or term. Conversely, adding optional products or other charges to the loan can increase the amount financed and therefore the payment and interest. Ask for the amount financed and the payment schedule as separate line items so the arithmetic can be checked.

Limits and Common Misunderstandings

• APR is not the monthly rate. The calculator converts annual percentage APR to a monthly rate by dividing by 12 after converting the percentage to a decimal, or equivalently dividing the entered percentage by 1,200.
• The result is not a quote. The calculation uses the inputs provided. It does not predict an approval decision, available terms, or the final figures in a financing contract.
• Taxes and fees are not automatically included. Add them to the amount financed only if they are part of the actual amount being borrowed; otherwise, keep them separate.
• Rounding affects totals slightly. The displayed monthly payment is rounded to cents, and the interest estimate uses that rounded amount multiplied by the number of payments. A lender’s schedule may handle rounding and the final payment differently.
• Extra payments are not modelled. The formula assumes scheduled, equal payments and no changes to the balance or rate.

At a zero interest rate, the payment would simply be the amount financed divided by the number of monthly payments. This calculator requires an APR of at least 0.01%, so that special case is not entered as zero. For variable-rate loans, changing payment schedules, or irregular payment dates, this fixed-rate estimate will not reproduce the full account calculation.

Frequently Asked Questions

How do I calculate a new car payment?
Use the amount financed, monthly interest rate, and number of monthly payments in the amortizing-loan formula shown above. The calculator applies that formula and rounds the monthly payment to cents.

Does a car payment include insurance?
No. The estimated payment covers principal and interest only. Insurance and other ownership expenses should be considered separately.

Will a longer loan term lower my payment?
For the same amount financed and APR, spreading repayment over more months generally lowers each scheduled payment. It also increases the number of payments, so total interest can be higher.

Should I use the sticker price or amount financed?
Use the amount financed for the loan-payment calculation. It may differ from the sticker price because of a down payment, trade-in, taxes, fees, or other items included in the financing.

Why does my lender’s payment differ from this estimate?
The lender may use different input figures, include financed charges, apply different rounding, or calculate a final payment differently. Compare the calculator’s assumptions with the lender’s itemized loan disclosure.

This result is an estimate; the lender’s disclosure gives the exact figures.

Related

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in p | Loan amount | $ | 20000 | 1 | 100000000
in apr | Interest rate (APR) | % | 8 | 0.01 | 100
in yrs | Loan term | years | 5 | 0.0833 | 50
out pmt | Monthly payment | $ | p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)) | 2
out int | Total interest | $ | pmt * yrs * 12 - p | 2