How to Calculate Auto Loan Payments: Formula and Example

 

To calculate a fixed auto loan payment, you need the amount financed, the interest rate, and the number of monthly payments. The vehicle price alone does not tell you how much you will borrow or repay.

Use the Auto Loan Payment Calculator for a fully amortizing fixed-rate monthly illustration.

Step 1: find the amount financed

Use the actual loan amount from the offer where available. A down payment reduces borrowing. A trade-in and any loan attached to it need to be accounted for, and taxes or fees may be paid upfront or financed. This tool does not assume a local tax rate or trade-in credit rule.

Step 2: convert the interest rate

The formula uses a nominal annual interest rate, converted to a monthly decimal rate. At 6% per year, the monthly rate is 0.06 / 12 = 0.005. APR may include fees and differ from this rate, so do not assume the two always produce the same payment.

Step 3: enter the term in months

For a five-year loan with monthly payments, N is 60. This model assumes the first payment is due at the end of the first equal monthly period. It does not model a deferred first payment, exact calendar dates, or daily interest.

The auto loan payment formula

Payment = P x r / (1 - (1 + r)^(-N)).

• P is amount financed.
• r is monthly interest rate as a decimal.
• N is number of monthly payments.

Example: $25,000 at 6% for 60 months

Using P = $25,000, r = 0.005, and N = 60 gives approximately $483.32 per month. The unrounded theoretical payment is about $483.320038.

Total modeled repayment is approximately $28,999.20. Subtracting the $25,000 principal gives approximately $3,999.20 in interest. These totals use the unrounded payment, not 60 times its displayed two-decimal value. A lender may round installments and adjust the final payment differently.

How to calculate a 0% car loan

At 0%, divide principal by the number of months. Financing $24,000 over 60 months gives $400 per month and no modeled interest. Fees and other costs can still apply to an actual offer.

Why term length matters

With the same principal and positive rate, a longer term generally lowers the monthly payment but increases total interest in this model. Compare both outputs and account for insurance, maintenance, fuel, and other ownership costs separately.

What the calculator does not determine

The result is not lender approval or a quote. It does not predict the interest rate you will qualify for, calculate credit eligibility, or model a lease, balloon balance, variable rate, taxes, unentered fees, or exact daily-interest schedule.

Frequently asked questions

Can I use the original vehicle price?

Only if it equals the amount actually financed. Otherwise use the loan amount after the relevant down payment, trade-in settlement, and financed charges are accounted for.

Why does my lender show a different payment?

Differences may come from rate definitions, financed fees, first-payment timing, daily interest, rounding, or a different amount financed. Compare the contract details.

Can I compare early payoff?

Use our Car Loan Payoff Calculator for a current balance, existing payment, and recurring extra payment. That is a different question from estimating the original monthly payment.

Try the Auto Loan Payment Calculator to compare fixed-rate monthly scenarios.