Car Loan Payment Calculator Payoff and Interest

A car loan payment calculator estimates your fixed monthly payment and the total interest over the scheduled term from the amount borrowed, APR, and loan length. Enter those three figures to see the payment and interest estimate; it does not calculate an early payoff date or account for lender-specific fees.

Formula

The calculator uses the standard fixed-payment amortizing-loan formula. Monthly payment equals principal times the monthly interest rate, divided by one minus (one plus the monthly rate) raised to the negative number of monthly payments:

Payment = P × r / (1 − (1 + r)−n)

• P is the amount financed, in dollars.
• r is the monthly interest rate as a decimal: APR (%) ÷ 1,200.
• n is the number of monthly payments: loan term in years × 12.
• Payment is the estimated monthly principal-and-interest amount, in dollars.

Total interest is calculated as the rounded monthly payment multiplied by the number of payments, minus the original principal: Total interest = Payment × n − P. The displayed payment is rounded to cents, so the interest estimate uses that rounded amount. A real lender may handle the final payment or rounding differently.

Worked Example

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

1. Convert APR to a monthly decimal rate: r = 8 ÷ 1,200 = 0.0066667.
2. Find the number of payments: n = 5 × 12 = 60.
3. Substitute into the payment formula: 20,000 × 0.0066667 ÷ (1 − (1.0066667)−60), which rounds to $405.53 per month.
4. Calculate total interest using the displayed payment: $405.53 × 60 − $20,000 = $4,331.80.

Assumptions

• The loan has a fixed APR and equal monthly payments.
• Payments are made monthly; the calculation treats them as scheduled at the end of each monthly period.
• Interest compounds monthly at APR divided by 12.
• The calculation excludes fees, taxes, insurance, optional products, and other amounts that may be included in a vehicle transaction or payment.

How to Read a Car Loan Payment Estimate

The monthly payment is an estimate of principal and interest under the entered terms, not necessarily the full amount due each month. Your actual bill may include other charges, and the amount financed may differ from a car’s advertised price. For an estimate that reflects the loan itself, use the amount the lender will finance after considering the agreed transaction figures, any down payment, and any trade-in credit or balance being carried over.

The total-interest output is the estimated interest over all scheduled payments if the loan runs its full term and payments are made as assumed. It is not the total amount paid: add the principal to interest to get the scheduled repayment total. In the example, that sum is $24,331.80. A longer term generally means more payment periods; the actual interest total depends on the entered APR, principal, term, and payment schedule.

Payoff: Scheduled Term Versus Early Repayment

“Payoff” can mean either the amount paid across the full scheduled term or the amount needed to close the loan on a particular date. This calculator estimates the first. It does not determine an exact early payoff quote, because that figure depends on the lender’s account balance, payment posting, accrued interest, and any contract-specific charges or adjustments.

Making extra payments can change the time required to repay a balance and the interest charged, but the calculator has no extra-payment input. Do not simply subtract extra payments from the displayed total-interest figure to estimate savings: payment timing and the way the lender applies additional money affect the result. Ask the lender how to obtain a current payoff quote and how to designate any additional payment toward principal. Continue to follow the required payment schedule until the account is confirmed paid off.

Inputs, Common Errors, and Limits

• Use APR as a yearly percentage. Enter 8 for 8%, not 0.08 or 8 as a monthly rate. The formula converts the annual percentage to a monthly decimal.
• Enter the loan term in years. The calculator multiplies it by 12. For example, five years means 60 payments.
• Use the amount financed, not automatically the vehicle price. A down payment, trade-in, taxes, and other transaction amounts may change the principal; check the lender’s figure rather than guessing.
• Expect small differences from a lender’s schedule. Payments are rounded to cents, while a lender’s system may calculate daily interest, adjust for payment dates, or use a different final-payment amount.

The formula assumes an ordinary fully amortizing loan: every scheduled payment is the same, the rate stays fixed, and the payment is sufficient to cover interest and reduce principal. It does not model variable rates, skipped or late payments, irregular schedules, balloon payments, or fees rolled into a balance unless those amounts are reflected in the principal or terms entered. A zero APR is not an allowed input here because this calculator’s payment expression divides by the monthly rate; for a genuinely interest-free loan, principal divided by the number of payments gives the level payment.

Frequently Asked Questions

Does this calculator show my exact car loan payoff amount?
No. It estimates the scheduled payment and full-term interest. Request a dated payoff quote from the lender for the amount required to close the account.

Does the monthly payment include insurance and taxes?
No. The estimate covers principal and interest only. Insurance, taxes, fees, and other charges are not included unless they are part of the loan amount you enter.

Why is my lender’s payment different?
The financed amount, APR, term, payment dates, rounding, and included charges may differ from your inputs or from the formula’s assumptions. Compare the lender’s disclosed figures with the values entered.

Can I use this to calculate savings from extra payments?
Not directly. There is no extra-payment input, and savings depend on the additional amount, when it is applied, and how the lender handles it. A balance and payment schedule that includes those details is needed.

What does total interest mean?
It is the estimated sum of interest across the scheduled payments, not the total repayment amount. Add it to principal to estimate the total paid under the calculator’s assumptions.

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

Related

• Car Loan Calculator With Down Payment: Monthly Car Payment
• Auto Loan Calculator With Trade-In and Amount Owed (Negative Equity)

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