Determine the loan amount for the car purchase, for example $20,000.
Find the interest rate from the lender, for example 5%.
Convert the interest rate from a percentage to a decimal, which is 0.05.
Multiply the loan amount by the interest rate, e.g., $20,000 x 0.05 = $1,000.
Divide the monthly interest by 12 to get the monthly interest payment, e.g., $1,000 / 12 = $83.33.
Add the monthly interest payment to the loan amount, e.g., $83.33 + $20,000 = $20,083.33.
Divide the total monthly payment by the number of months in the loan term, e.g., $20,083.33 / 60 months = $334.72.
Round the result to the nearest cent to get the monthly car payment, e.g., $334.72.
Consider any additional fees, such as taxes or insurance, and add them to the monthly payment calculation.
If applicable, subtract any down payment made towards the car purchase from the loan amount.
Factor in the loan term, such as 36, 48, or 60 months, to determine the monthly payment.
Keep in mind that longer loan terms may result in lower monthly payments, but higher overall interest costs.