Calculate My New Car Payment? Estimate It Here

Calculate an estimated monthly car payment by entering the amount financed, annual percentage rate (APR), and loan term. The calculator returns the monthly payment and total interest for a fixed-rate loan with equal monthly payments; it does not include taxes, fees, insurance, or other ownership costs.

Formula

The calculator uses the standard fixed-payment loan formula, rounding the monthly payment to the nearest cent before calculating total interest:

Monthly payment = round[P × r ÷ (1 − (1 + r)⁻ⁿ), 2]

• 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.
• n is the number of monthly payments, calculated as loan term in years × 12.
• Total interest = rounded monthly payment × n − P, in dollars.

The amount financed is the principal used in the calculation, not necessarily the car’s advertised price. A down payment or trade-in may reduce the amount borrowed, while any amount rolled into the loan may increase it. The formula assumes the same interest rate and payment amount throughout the term.

Worked Example

Using the calculator’s default inputs—$20,000 financed, 8% APR, and 5 years:

1. Convert APR to a monthly rate: 8 ÷ 1,200 = 0.0066667, or about 0.66667% per month.
2. Convert the term to payments: 5 × 12 = 60 monthly payments.
3. Substitute into the formula: $20,000 × 0.0066667 ÷ [1 − (1.0066667)⁻⁶⁰] = $405.53 after rounding to cents.
4. Calculate total interest using the rounded payment: $405.53 × 60 − $20,000 = $4,331.80.

For these inputs, the estimated monthly payment is $405.53, and estimated total interest is $4,331.80. The total of the 60 rounded payments is $24,331.80, including the original $20,000 principal.

Assumptions

• The interest rate is fixed for the full loan term.
• Payments are equal, made monthly, and assumed to occur at the end of each monthly period.
• Interest compounds monthly using APR ÷ 12 as the periodic rate.
• The estimate excludes taxes, registration and dealer fees, insurance, add-ons, and other charges unless they are included in the amount financed.

What to Enter for a Car Estimate

To estimate a particular deal, first work out the amount you expect to finance. Begin with the vehicle price and include any costs that the lender or sales paperwork says will be financed. Subtract any down payment, trade-in credit, or other amount applied to the purchase. Use the actual loan amount and APR quoted for the specific transaction rather than assuming that the vehicle price is the principal.

Enter the APR as a yearly percentage: for example, enter 8 for 8%, not 0.08. Enter the contract term in years. The calculator converts years to months, so a five-year term means 60 payments. If the lender provides a term in months that does not convert neatly into years, this calculator may not represent that exact term; do not treat a rounded year entry as the contract figure.

APR and the interest rate can be presented differently in loan documents, especially where fees affect the annualized cost. For this estimate, use the APR figure supplied for the loan and confirm with the lender how the quoted payment is calculated. The calculator does not independently derive APR from fees.

How to Read the Payment and Total Interest

The monthly payment is the scheduled amount for principal and interest under the stated assumptions. In an amortizing loan, early payments generally include a larger interest portion than later payments: interest is calculated on the remaining balance, which declines as principal is repaid. The total-interest result adds the estimated interest across the scheduled payments. It is not the total amount paid for owning or operating the car.

Payment size depends on all three inputs. A larger amount financed raises the payment; a higher APR raises the interest cost; and a longer term usually lowers the scheduled monthly payment while increasing the number of months over which interest accrues. These are mathematical effects, not a recommendation about which loan term or contract to choose. The calculator does not assess household budgets, loan approval, or whether a vehicle is affordable.

Because the payment is rounded to cents before total interest is calculated, the displayed total uses the rounded payment multiplied by the full number of months. A lender’s final schedule may differ slightly due to its precise payment dates, rounding methods, first-payment timing, or contract terms.

Common Mistakes and Limits

• Using the sticker price as the loan amount: the financed principal may differ after down payment, trade-in, taxes, fees, or other financed items.
• Entering APR in the wrong format: enter 8 for 8%, not 0.08 or 8.00 as a decimal fraction.
• Mixing years and months: the term input is in years, and the calculation multiplies it by 12.
• Assuming the result is the full car budget: insurance, fuel, maintenance, parking, and other expenses are outside this loan calculation.
• Ignoring the payment schedule: an irregular first period, changing rate, balloon payment, or payment frequency other than monthly is not represented by this formula.

This is a mathematical estimate for a level-payment, fixed-rate loan. It cannot reproduce every contract feature, and it does not determine the lender’s fees, quoted APR, or final amount financed. Obtain the transaction’s exact figures from the lender’s written disclosure.

Frequently Asked Questions

How do I calculate a car payment by hand?
Convert APR to a monthly decimal by dividing the percentage by 1,200, and convert the term to months. Apply the fixed-payment formula shown above, then round the payment to cents. The calculator performs those steps automatically.

Does a down payment lower my monthly payment?
It lowers the payment if it reduces the amount financed and the APR and term stay the same. Enter the resulting loan principal—not the vehicle price—to estimate that payment.

Why does a longer car loan often have more total interest?
A longer term means more monthly periods in which interest can accrue. It can reduce the scheduled payment while increasing total interest under otherwise identical assumptions.

Does this estimate include sales tax and insurance?
No. It includes only the principal you enter and the modeled interest. Include a charge in the loan amount only if it will actually be financed; insurance and other ongoing costs are not calculated.

Why might the lender’s payment differ from this result?
The contract may use a different amount financed, APR, term, payment date, rounding convention, or additional loan feature. Compare the calculator inputs with the lender’s disclosure to identify the difference.

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

Related

• Loan Amortization in Office 365: What It Can Do
• Loan Amortization Interest Formula and Calculator
• Loan Amortization in QuickBooks Online Explained

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 | $ | round(p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)), 2) | 2
out int | Total interest | $ | pmt * yrs * 12 - p | 2