Car Payment Calculator: Estimate Your Monthly Payment

A car payment calculator estimates the monthly principal-and-interest payment on a vehicle loan from the amount borrowed, annual percentage rate (APR), and loan term. Enter those three figures to see the estimated monthly payment and total interest; the result does not include costs such as taxes, insurance, or vehicle upkeep.

Formula

The calculator uses the standard fixed-payment loan formula. It converts the annual APR to a monthly rate, then calculates the payment that repays the principal and interest over the selected number of monthly payments.

• Monthly payment: M = round[P × r ÷ (1 − (1 + r)⁻ⁿ), 2]
• Total interest: I = (M × n) − P
• Monthly rate: r = APR ÷ 1,200
• Number of payments: n = years × 12

Here, P is the amount borrowed in dollars, APR is the annual percentage rate entered as a percentage, r is the monthly interest rate as a decimal, n is the number of monthly payments, M is the monthly payment in dollars rounded to cents, and I is total interest in dollars. The total-interest result uses the displayed, cent-rounded payment.

Worked Example

Using the calculator’s default inputs—$20,000 borrowed, 8% APR, and a five-year term:

1. Convert APR to a monthly rate: 8 ÷ 1,200 = 0.0066667.
2. Convert the term to payments: 5 × 12 = 60 months.
3. Apply the payment formula: $20,000 × 0.0066667 ÷ [1 − (1 + 0.0066667)⁻⁶⁰] = $405.53 per month, rounded to the nearest cent.
4. Calculate interest using the rounded payment: ($405.53 × 60) − $20,000 = $4,331.80.

The estimated monthly payment is $405.53, and estimated total interest is $4,331.80. Totals can differ slightly from a lender’s final figures because of payment timing, rounding conventions, and loan details not represented here.

Assumptions

• The APR remains fixed for the full loan term.
• There are equal monthly payments, with the first payment one month after borrowing.
• Interest compounds monthly at APR divided by 12.
• The calculation excludes origination or other fees, sales taxes, registration, insurance, maintenance, and optional products. It does not model a down payment or trade-in separately; subtract those from the vehicle’s financed amount before entering the loan amount.

What Goes Into a Car Payment?

A quoted car payment depends on the amount financed, the APR, and the term. The amount financed is not necessarily the advertised vehicle price: it can reflect a down payment, trade-in value, taxes and fees added to the loan, and any existing balance rolled into a new loan. Enter the amount the lender would actually finance if you have it, rather than assuming it equals the sticker price.

For example, a $25,000 vehicle price with $3,000 paid upfront does not automatically mean the loan is $22,000. Taxes or fees may be financed, while a trade-in or other credits may reduce the amount. The final figure depends on the transaction. Get the actual amount, APR, and term from the lender’s written figures and use them as calculator inputs.

How to Read and Use the Estimate

The monthly payment is the regular amount implied by the entered loan terms under the assumptions above. Total interest estimates the cost of borrowing over the full schedule; it is not the total price of owning or operating the car. To estimate the total of loan payments, add the original principal to the interest result. Other transaction costs are separate unless they were included in the amount financed.

Try changing one input at a time to see how the arithmetic responds. A longer term generally spreads repayment over more months and can lower the calculated monthly amount, while increasing the number of months over which interest accrues. A higher APR increases the payment and interest under the same principal and term. These are mathematical effects, not a judgment about which loan terms suit an individual.

Common Questions About the Estimate

Use consistent units: APR is entered as a percentage per year, such as 8 for 8%, not as 0.08. The formula converts it to a monthly rate. The term is entered in years, so a 60-month term is five years. Small differences in rounding are normal: this calculator rounds the payment to cents and then uses that rounded payment to calculate total interest.

A payment estimate also is not an approval decision or a complete affordability assessment. The calculator cannot assess income, expenses, credit information, lender criteria, or whether a particular loan is available. It only applies the stated formula to the numbers entered.

Frequently Asked Questions

Does a car payment include insurance and taxes?
No. This estimate covers principal and interest on the loan only. Insurance and vehicle operating costs are excluded. Taxes and fees are excluded unless they are included in the amount you enter as the loan principal.

Why is my lender’s payment different?
The lender may use a different financed amount, payment dates, rounding method, or fee treatment. Check the loan amount, APR, term, and payment schedule in the lender’s disclosure, and compare them with the calculator inputs.

Should I enter the car’s price or the amount financed?
Enter the amount borrowed. If the lender has not supplied that figure, account for the down payment, trade-in, and any taxes or fees included in the loan before estimating it.

Does a longer loan term reduce the total cost?
The calculator shows the arithmetic for the chosen term. A longer term can reduce the scheduled monthly payment while increasing total interest because payments continue for more months. It does not assess other costs or personal circumstances.

Can I use this for a variable-rate loan?
This formula assumes a fixed APR. If the rate can change, the actual payment or total interest may change too, and this estimate will not model those changes.

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

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