Car Loan Estimate: Monthly Payment Calculator

This car loan calculator estimates your monthly principal-and-interest payment from the amount borrowed, annual percentage rate (APR), and loan term. Enter those figures to see the payment and estimated total interest; taxes, fees, insurance, and other costs are not included.

Formula

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

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

• P is the amount borrowed, in dollars.
• r is the monthly interest rate, calculated as APR ÷ 1,200. For an 8% APR, r = 0.08 ÷ 12, or about 0.006667 per month.
• 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 loan amount: total interest = monthly payment × n − P. The calculator rounds the payment to cents before using it in this total, so the displayed figures reflect a payment made in whole cents.

Worked Example

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

1. Monthly rate: 8 ÷ 1,200 = 0.0066667.
2. Number of payments: 5 × 12 = 60.
3. Substitute into the payment formula: $20,000 × 0.0066667 ÷ [1 − (1 + 0.0066667)⁻⁶⁰].
4. Monthly payment, rounded to cents: $405.53.
5. Estimated total of payments: $405.53 × 60 = $24,331.80.
6. Estimated total interest: $24,331.80 − $20,000 = $4,331.80.

Assumptions

• The APR and payment amount stay fixed for the full term.
• Payments are monthly and made at the end of each monthly period.
• Interest is modelled monthly at APR divided by 12.
• The estimate excludes fees, taxes, insurance, optional products, and other charges unless they are included in the amount borrowed.

What the Estimate Includes

A car-loan payment estimate is the scheduled amount for repaying borrowed principal and interest under the stated assumptions. It is not necessarily the full monthly cost of owning or operating a vehicle. A real bill may also include items such as insurance or charges collected with the loan, and expenses such as fuel and maintenance are separate.

Use the amount actually financed as the loan amount. A vehicle’s advertised price, negotiated price, down payment, trade-in value, and the final amount borrowed are different figures. If a down payment or trade-in reduces what you borrow, reflect that in the principal. If a fee or other item is added to the financing, include it only if it is part of the loan amount shown by the lender.

APR is entered as a yearly percentage, not as a decimal or a monthly rate. The calculator performs the conversion itself. For example, enter 8 for 8%, not 0.08 or 0.00667. Use the APR and term supplied for the specific estimate you are examining; the default figures are only an arithmetic example, not a prediction of an offer or a rate available to any borrower.

How Term and APR Affect Payments

For the same principal and APR, extending the term generally lowers the scheduled monthly payment because repayment is spread over more months. It also means more payments accrue interest. Shortening the term generally raises each payment while reducing the number of payment periods. The exact difference depends on the amount, APR, and term together, so changing only one field at a time can help show how the estimate responds.

A higher APR increases the payment and estimated interest when the amount and term remain unchanged. Conversely, a lower APR reduces them under the same assumptions. These are mathematical relationships, not statements about what rate a person may receive. Obtain the applicable rate, financed amount, term, and any charges directly from the lender’s written figures.

Common Estimate Mismatches

• Comparing different amounts financed: A quote that includes financed fees or optional items will not match a calculation using only the vehicle price.
• Using a different APR or term: Even a small input difference changes the scheduled payment. Confirm that the figures refer to the same proposed loan.
• Expecting the estimate to equal every bill: This calculation covers principal and interest only; it does not add insurance, taxes, or other excluded costs.
• Rounding at different stages: The payment is rounded to cents. A lender’s schedule may also account for payment dates, rounding, or a final adjustment, so a small difference can occur.
• Assuming a lower payment means a lower overall cost: A longer term can reduce the monthly amount while increasing the number of payments and the total interest under otherwise equal assumptions.

This is a level-payment estimate, not a full amortization schedule. In an amortizing loan, each payment covers interest accrued for that period and reduces the remaining principal; the split changes over time. Actual contracts may use payment dates or calculation conventions that differ from the simplified monthly model here.

Frequently Asked Questions

How do I estimate a car loan payment?
Enter the amount financed, annual APR, and term. Convert APR to a monthly rate by dividing by 1,200, convert years to months by multiplying by 12, and apply the fixed-payment formula shown above.

Does the estimate include a down payment?
No. A down payment is not itself part of the loan payment formula. Account for it when determining the amount actually borrowed; enter that financed amount as the loan principal.

Does a car loan payment estimate include insurance and taxes?
No. This calculator estimates principal and interest. Insurance and taxes, as well as fees or other charges, are excluded unless included in the amount financed.

Why is my lender’s payment different?
The lender may use a different APR, principal, term, payment date, fee treatment, or rounding method. Compare the inputs and ask the lender how its quoted payment is calculated.

Does choosing a longer term reduce total interest?
Not necessarily. With the same principal and APR, a longer term usually lowers each scheduled payment but adds payment periods, which can increase total interest.

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

Related

• JC Credit Card Payment: Calculate Your Monthly Payment
• How to Order a Payoff: Steps and What to Check
• How to Pay a J.Crew Credit Card

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