calculate-loan

01 Loan payments

Auto Car Loan Calculator: Estimate Monthly Payments

Calculator No. 01-6788 · Updated · Formula and assumptions shown below

Monthly payment $405.53
Total interest
$4,331.80
= Monthly payment × loan term × 12 − loan amount
Loan amount
$20,000
Input
Interest rate (APR)
8 %
Input
You enter
Loan amount ($), Interest rate (APR) (%), Loan term (years)
You get
Monthly payment ($), Total interest ($)
Rounding
2 dp

Estimate for education, not financial advice. The result follows from the numbers you enter and the formula shown. It is not a quote or an offer, and it does not include fees, taxes or insurance unless the calculator asks for them. Ask your lender for the exact figures.

An auto car loan calculator estimates your fixed monthly principal-and-interest payment from the amount financed, annual percentage rate (APR), and loan term. Enter those three figures to see the payment and estimated total interest; the calculation does not include taxes, fees, insurance, or other ownership costs.

Formula

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

Monthly payment = round[P × r ÷ (1 − (1 + r)−n), 2]

  • P is the amount financed, in dollars.
  • r is the monthly interest rate, calculated as APR ÷ 1,200. APR is entered as a percentage per year; for example, 8 means 8%.
  • n is the number of monthly payments, calculated as loan term in years × 12.
  • round means the payment is rounded to the nearest cent.

Estimated total interest is monthly payment × n − P, in dollars. Because this uses the rounded monthly payment, the total reflects the displayed payment multiplied by the number of payments. A lender’s final schedule may differ because of its exact payment dates, rounding method, fees, or contract terms.

Worked Example

Using the calculator’s default values—$20,000 financed, 8% APR, and a 5-year term—the calculation is:

  1. Monthly rate: 8 ÷ 1,200 = 0.0066667.
  2. Number of payments: 5 × 12 = 60.
  3. Payment before rounding: $20,000 × 0.0066667 ÷ [1 − (1.0066667)−60] ≈ $405.53.
  4. Monthly payment rounded to cents: $405.53.
  5. Estimated total interest: $405.53 × 60 − $20,000 = $4,331.80.

Assumptions

  • The interest rate is fixed for the full term.
  • Payments are equal monthly installments, with the first payment one month after the loan begins.
  • Interest accrues monthly using APR divided by 12; the APR is treated as a nominal annual rate for this estimate.
  • The calculation excludes fees, taxes, insurance, down payment, trade-in value, and other charges unless they are already reflected in the amount financed. It also excludes maintenance and fuel.

What to Enter and How to Read the Results

Loan amount means the amount borrowed, not necessarily the vehicle’s advertised price. A down payment or trade-in credit can reduce the amount financed; taxes, optional products, and fees included in the contract can increase it. For a useful estimate, use the amount the lender expects to finance rather than the vehicle price alone.

APR is the annual percentage rate provided in a lender’s offer or estimate. Use the figure from the relevant disclosure, not a rate guessed from a general source. APR and the interest rate used to accrue interest are related but can be affected differently by fees and the lender’s calculation method. This calculator uses APR as its rate input and does not separately model financed fees.

Loan term is the time allowed for repayment, in years. The calculator converts it to months, so a 5-year term means 60 payments. A longer term spreads repayment across more months and generally produces a smaller scheduled payment for the same principal and rate, while the loan remains outstanding longer. At a positive rate, that usually means more total interest. The exact figures depend on the inputs and payment schedule.

The monthly payment is only the estimated installment for repaying the loan. It is not the total monthly cost of owning or operating a car. Insurance, fuel, repairs, registration, parking, and other expenses are separate. The total-interest output is an estimate for the full schedule, not an extra monthly charge. It is the estimated amount paid above the original principal when the rounded payment is multiplied by all scheduled months.

Common Mistakes and Calculation Limits

  • Entering the vehicle price as the loan amount: Adjust for the down payment, trade-in, and any costs included in financing before entering the amount financed.
  • Entering APR as a decimal: Type 8 for 8%, not 0.08. The formula divides the entered percentage by 1,200 to produce a monthly decimal rate.
  • Mixing years and months: This calculator asks for years. Entering 60 would mean 60 years, not 60 months. For a 60-month term, enter 5.
  • Treating the result as a quote: The calculation does not know a lender’s fees, payment dates, contract provisions, or rounding practices. Use the lender’s disclosed figures to verify an actual offer.
  • Rounding intermediate values: The displayed payment is rounded to cents. Small differences can arise when a lender calculates with more precision internally or adjusts the first or final payment.

The formula assumes a fixed rate and equal payments. It is not designed to model a variable rate, irregular payment schedule, balloon payment, skipped installments, late charges, or extra principal payments. If a contract has one of these features, its payment schedule may not match this estimate. The input limits are calculation boundaries, not statements about what any lender offers or permits.

Frequently Asked Questions

How do I calculate a monthly car loan payment?
Convert APR to a monthly rate by dividing the percentage by 1,200, convert the term to months, and apply the fixed-payment formula shown above. The calculator performs these steps and rounds the estimated payment to cents.

Does a car loan payment calculator include taxes and insurance?
Not in this calculator. It estimates principal and interest only. Include applicable costs in the loan amount only if they are being financed, and budget separately for costs that are paid outside the loan.

Why does a longer auto loan term lower the monthly payment?
The same principal is divided across more monthly payments. With a positive rate, interest accrues while the balance remains unpaid, so a longer schedule can increase total interest even when its scheduled payment is lower.

Is the calculator’s payment the amount a lender will charge?
Not necessarily. It is an estimate under the assumptions listed above. A lender’s contract may include charges or timing details this calculator does not model; check the lender’s disclosure for exact figures.

What if I make an extra payment?
This calculator assumes the scheduled fixed payment only, so it does not estimate an early payoff date or interest savings from extra payments. Those depend on when additional amounts are paid and how the lender applies them to the balance.

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

Related

Formula used
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

Each line is one input (in, sel, list) or one result (out: label, unit, formula, decimals). How the calculators work

Method: the standard loan formula for this calculation, fixed rate and monthly compounding unless stated, rounded as each result states. Not financial advice; no lender, rate or product is recommended. See formulas and assumptions, the disclaimer or report an error.

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