Car Loan Total Calculator: Payment, Interest and Cost

A car loan total calculator estimates your monthly payment, total interest, and total of scheduled payments from the amount financed, APR, and loan term. Enter those figures to see the estimated cost of the loan itself; taxes, insurance, and other charges are not included unless they are part of the amount financed.

Formula

The calculator uses the standard fixed-rate amortizing-loan payment formula. It converts the annual percentage rate (APR) to a monthly rate, calculates a level monthly payment, rounds that payment to cents, then multiplies it by the number of monthly payments.

• P is the amount financed, in dollars.
• APR is the annual percentage rate, entered as a percentage per year.
• r is the monthly rate: APR ÷ 1,200.
• n is the term in months: years × 12.
• M is the monthly payment, in dollars.
• T is total scheduled payments, in dollars; T = M × n.
• I is total interest under this estimate, in dollars; I = T − P.

In symbols, the unrounded payment is M = P × r ÷ [1 − (1 + r)⁻ⁿ]. The calculator rounds M to the nearest cent before calculating T and I. This matters because multiplying a rounded monthly payment gives a total that can differ slightly from a calculation using an unrounded payment.

Worked Example

Using the default values—$20,000 financed, 8% APR, and a five-year term:

1. Convert the term: n = 5 × 12 = 60 monthly payments.
2. Convert the APR to a monthly rate: r = 8 ÷ 1,200 = 0.0066667.
3. Calculate the payment: M = 20,000 × 0.0066667 ÷ [1 − (1.0066667)⁻⁶⁰] ≈ $405.53 per month, rounded to cents.
4. Calculate scheduled payments: T = $405.53 × 60 = $24,331.80.
5. Subtract the amount financed: I = $24,331.80 − $20,000 = $4,331.80.

For these inputs, the estimated monthly payment is $405.53, the total of scheduled payments is $24,331.80, and the estimated total interest is $4,331.80.

Assumptions

• The interest rate stays fixed for the full term.
• Payments are equal, made monthly, and begin on the schedule assumed by a standard amortization calculation.
• Interest is modelled monthly at APR ÷ 12; the lender’s exact calculation and payment dates may differ.
• The estimate excludes fees, taxes, insurance, down payment, trade-in value, and optional products unless they are already included in the amount financed. It does not calculate insurance, PMI, or escrow.

What the Total Includes—and Leaves Out

“Total cost” can mean different things. This calculator’s total of scheduled payments is the sum of principal and interest payments over the loan term. It is not necessarily the full cost of buying or owning a vehicle. A down payment is paid outside the loan, while a financed fee or add-on increases the amount borrowed and therefore affects the estimate. Sales taxes, registration, fuel, maintenance, repairs, and insurance are not calculated here.

To model a vehicle purchase, first distinguish the vehicle’s transaction price from the amount financed. The amount financed may be affected by a down payment, trade-in credit, taxes, fees, or products added to the contract. Use the amount that the lender says is being financed, not automatically the advertised vehicle price. Get the applicable APR, term, amount financed, and any charges from the written lender figures; the default values are examples, not a statement about available rates or fees.

How to Use and Read the Estimate

Enter the principal actually financed, the APR as a percentage (for example, enter 8 for 8%), and the term in years. The output is a mathematical estimate for a level-payment loan. The monthly payment includes both interest and principal; early payments generally allocate a larger share to interest in an amortizing loan, while the principal balance falls over time.

• Compare the same amount financed and APR when examining different terms; otherwise, several inputs change at once.
• Read total payments alongside monthly payment. A longer term can lower the scheduled monthly amount while increasing the number of payments, so it can increase total interest when other inputs are held constant.
• Check whether quoted charges are paid upfront or financed. Upfront charges are not part of this loan-payment total; financed charges are reflected only if included in P.
• Use the lender’s payment schedule for exact due dates, rounding, and final-payment details.

A common misconception is that APR alone determines the total paid. The amount financed and term also matter, and fees may affect a lender’s disclosed APR or the financed balance. This calculator does not infer those figures. Enter the contract’s relevant values rather than trying to estimate them from a vehicle price or a monthly-payment advertisement.

Common Calculation Limits

The formula assumes a fixed APR and regular, equal monthly payments. It does not model a variable rate, a balloon payment, skipped or irregular payments, late charges, or an early payoff. Extra principal payments would usually change the balance and interest path, but they are not included in the scheduled-payment total shown here.

Rounding can also cause small differences. The displayed payment is rounded to cents and then multiplied by the full number of payments, as shown above. A lender may calculate interest using its own day-count method, apply payments on specific dates, or adjust the final installment. Consequently, this result is useful for understanding the arithmetic, but it is not a payoff quote or a substitute for a contract disclosure.

Frequently Asked Questions

How do I calculate the total cost of a car loan?
Calculate the fixed monthly payment from the amount financed, APR, and term, then multiply that rounded payment by the number of months. Subtract the amount financed from the payment total to estimate interest. This does not include costs outside the loan.

Does the total include my down payment?
No. The calculator totals scheduled loan payments only. Add any down payment separately if you are working out the combined amount paid toward the vehicle, while keeping taxes and other ownership expenses separate.

Why can a longer car loan cost more in interest?
With the same principal and APR, a longer term schedules more payments and leaves the balance outstanding for longer. It can reduce the monthly payment, but the total interest may rise. The calculator displays both figures so they are not confused.

Is APR the same as the interest rate?
APR is a yearly percentage used here as the loan’s annual rate input. A lender’s APR may reflect more than the stated interest rate, depending on the loan and disclosed charges. Use the actual APR quoted for the specific loan; this calculator does not determine it.

Why does my lender’s total differ from this estimate?
Differences can result from fees, payment dates, interest-accrual methods, rounding, a different amount financed, or contract terms this formula does not model. Compare the calculator inputs with the lender’s disclosure and payment schedule.

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

Related

• Car Loan Calculator: Total Interest Paid Explained
• Car Loan Calculator Monthly Payment and Payoff
• Car Loan Calculator QLD: Estimate Monthly Repayments

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 tot | Total of scheduled payments | $ | pmt * yrs * 12 | 2
out int | Total interest | $ | tot - p | 2