Calculate Total Car Loan Cost and Interest

Calculate total car loan cost by multiplying the monthly payment by the number of payments; the result is the total of scheduled loan payments, including principal and interest. Enter the amount financed, APR, and term to estimate the monthly payment and total interest; this calculator does not include a down payment, taxes, insurance, or other costs of owning the car.

Formula

The calculator uses a fixed-payment, amortizing-loan formula. It first calculates the monthly payment, rounded to the nearest cent, and then subtracts the amount borrowed from all scheduled payments to estimate interest:

• Monthly payment: M = round[P × r ÷ (1 − (1 + r)⁻ⁿ), 2]
• Total payments: T = M × n
• Total interest: I = T − P

Here, P is the loan principal in dollars, or the amount financed; APR is the annual percentage rate entered as a percentage; r is the monthly rate, APR ÷ 1,200; n is the number of monthly payments, loan term in years × 12; M is the monthly payment in dollars; T is the scheduled payment total in dollars; and I is estimated interest in dollars. For example, 8% APR becomes a monthly rate of 0.08 ÷ 12, or 0.0066667. The calculator displays payment and interest to cents.

Worked Example

Using the calculator’s defaults—$20,000 financed, 8% APR, and a five-year term—the calculation is:

1. Convert APR to a monthly rate: r = 8 ÷ 1,200 = 0.0066667.
2. Convert the term to payments: n = 5 × 12 = 60.
3. Calculate the monthly payment: M = round[20,000 × 0.0066667 ÷ (1 − (1.0066667)⁻⁶⁰), 2] = $405.53.
4. Calculate scheduled payments: $405.53 × 60 = $24,331.80.
5. Subtract principal: $24,331.80 − $20,000 = $4,331.80 total interest.

Because the payment is rounded to cents before totals are calculated, the result reflects 60 payments of $405.53. A lender’s exact payment schedule may differ slightly because of its rounding and payment-date conventions.

Assumptions

• The APR stays fixed throughout the loan.
• Payments are equal monthly payments made at the end of each monthly period.
• Interest accrues monthly at APR ÷ 12, as a standard loan estimate.
• The calculation excludes fees, taxes, insurance, down payment, trade-in value, optional products, and other charges unless included in the amount financed.

What Counts as Total Car Loan Cost?

“Total car loan cost” can mean either the total of payments due on the loan or the broader cost of acquiring and operating a car. This calculator reports the first meaning: principal plus scheduled interest. It does not calculate the vehicle’s full out-of-pocket cost over time.

The amount financed is not necessarily the car’s advertised price. A down payment or trade-in can reduce the principal. Conversely, charges or optional products added to the contract can increase it. To estimate the loan accurately, use the amount actually financed in the lender’s disclosure, not automatically the sticker price.

For a broader purchase budget, separately account for any cash paid upfront and costs such as registration, maintenance, fuel, and insurance. Those amounts depend on the vehicle and the buyer, and are not determined by a loan-payment formula.

How to Use and Interpret the Estimate

Enter the amount financed, the APR quoted for the loan, and the repayment term. The first output is the estimated monthly payment; the second is estimated interest over all scheduled payments. Add the principal to the interest to get the total scheduled payments. The example’s total is $20,000 + $4,331.80 = $24,331.80.

The APR and term must describe the same loan offer. If the lender provides a fixed monthly payment, comparing that figure with the estimate can help identify inputs that may be missing or different. Check whether the lender’s disclosed payment includes financed charges, and confirm the number and timing of payments. This arithmetic does not determine eligibility or predict the terms a lender will offer; enter the actual figures supplied for the specific loan.

What Changes the Total?

• Amount financed: A larger principal generally produces a larger payment and more interest when the rate and term are unchanged.
• APR: A higher entered APR increases the modeled interest and payment for a fixed principal and term.
• Loan term: A longer term usually spreads repayment over more months. It can reduce the monthly payment while increasing the number of months over which interest accrues.
• Extra payments or early payoff: These can change the real payment schedule and interest total. This calculator assumes the scheduled payment continues unchanged and does not model extra payments.

Do not confuse the monthly payment with the total cost. A smaller payment alone does not show that a loan has lower overall interest: the term and amount financed matter too. For an accurate comparison, calculate each offer using its own principal, APR, and term, and compare total scheduled payments alongside the monthly figure.

Common Calculation Limits

This standard formula assumes a fixed rate and regular end-of-month payments. It may not match a contract with a variable rate, irregular payment dates, a balloon payment, skipped or deferred payments, or fees paid separately. It also does not model a changing balance from extra principal payments.

Rounding matters: the calculator rounds each scheduled payment to cents and multiplies that rounded payment by the number of months. A lender may calculate interest daily, use different rounding rules, or adjust the final payment. APR may also reflect certain borrowing costs differently from the nominal interest rate, while this estimate uses APR divided by 12 as a monthly rate. Use the lender’s payment schedule and disclosure for the contract-specific amounts.

Frequently Asked Questions

How do I calculate the total paid on a car loan?
Multiply the monthly payment by the number of monthly payments. For the total loan cost including interest, this calculator’s total is the financed principal plus estimated interest.

Is total car loan cost the same as total interest?
No. Total interest is the borrowing cost estimated by this formula. Total scheduled payments include both the principal repaid and that interest.

Does this calculation include a down payment?
No. A down payment is paid separately and is not part of the amount financed. Include it separately when estimating the broader purchase outlay.

Why might my lender’s total differ?
The contract may use different payment dates, rounding, fees, financed add-ons, or interest-accrual methods. Compare the same amount financed, APR, and term, then refer to the lender’s disclosed schedule.

Does a longer term lower the total cost?
Not necessarily. It often lowers the scheduled monthly payment by spreading repayment over more months, but the longer repayment period can increase total interest. Calculate the offers with their actual terms to see the arithmetic.

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