What the Commercial Driver License exam tests

The Commercial Driver License (CDL) exam has three parts: written knowledge tests, a skills test behind the wheel, and a pre-trip vehicle inspection. You must pass all three to get your CDL. The written tests cover the rules of the road specific to large trucks or buses, how to handle them safely, and how to respond to emergencies. The skills test is a driving evaluation on a closed course or public roads with an examiner watching. The pre-trip inspection requires you to walk around the vehicle and point out working and broken parts while explaining what you are checking and why.

Each state runs its own CDL program, so the exact format, passing score, and testing locations vary by state. Most states require you to score at least 80 percent on the written tests. The skills test is usually pass or fail based on whether you can safely operate the vehicle and follow the examiner's instructions. You cannot use a personal vehicle for the skills test—you must bring a commercial vehicle that matches the class of license you are testing for.

Key Takeaways

  • The CDL exam has three parts: written knowledge tests, a behind-the-wheel skills test, and a pre-trip vehicle inspection, and you must pass all three.
  • Each state sets its own passing scores and testing procedures, so check your state's Department of Motor Vehicles website for the exact requirements and test locations.
  • You must bring a commercial vehicle that matches the class of CDL you are testing for; you cannot use a personal car.
  • Most states require you to pass a written permit test before you can schedule the skills test, and you must hold that permit for a set number of days.
  • The pre-trip inspection is not a written test—you walk around the vehicle and explain what you are checking while the examiner listens and watches.

The written knowledge tests and what they cover

The CDL written exam is divided into a general knowledge test that all CDL applicants must pass, plus additional tests depending on what you will be driving. The general knowledge test covers traffic laws, safe driving practices, vehicle control, and hazard perception. If you are testing for a passenger vehicle endorsement (to drive a bus), you take an additional passenger test. If you are testing to haul hazardous materials, you take a hazmat test. If you are testing to pull a double or triple trailer, you take an air brakes test or doubles/triples test depending on your vehicle type.

Each test is multiple choice, usually 50 questions, and you have a set time limit—typically 60 minutes. You study from your state's CDL manual, which is free and available online or at your local DMV office. The manual covers everything the test will ask about. Many people study the manual, take practice tests online, or attend a CDL training school. Some states allow you to take the written test at a third-party testing location (a private business licensed by the state), while others require you to test at the DMV office itself.

You must pass the general knowledge test before you can take any endorsement tests. Once you pass the general test, you can take the endorsement tests on the same day or schedule them separately. After you pass all the written tests you need, you receive a CDL permit (sometimes called a learner's permit), which allows you to practice driving a commercial vehicle with a licensed CDL holder in the passenger seat.

The CDL permit and how long you must hold it

After you pass the written tests, your state issues you a CDL permit. This permit allows you to drive a commercial vehicle for practice, but only with a licensed CDL holder sitting next to you. You cannot drive alone, and you cannot drive for pay. The permit is valid for a set period—most states allow 180 days (six months), though some allow longer.

During the permit period, you practice driving the vehicle you will test in. You learn how the brakes feel, how the steering responds, how to back up safely, and how to handle the vehicle in different road conditions. This practice time is critical because the skills test will ask you to perform specific maneuvers—backing in a straight line, backing into a space at an angle, turning without hitting cones, and driving on public roads while following traffic laws and the examiner's instructions.

Some states require you to hold the permit for a minimum number of days before you can schedule the skills test—often 14 days. This waiting period exists to may support you have had time to practice. If your permit expires before you pass the skills test, you must retake the written tests and get a new permit.

The pre-trip vehicle inspection test

The pre-trip inspection is a walk-around test where you point out and explain the condition of major vehicle systems. You start at one corner of the vehicle and work your way around, checking tires, lights, mirrors, wipers, brakes, coupling devices (if you are pulling a trailer), and other safety-critical parts. For each item, you tell the examiner what you are checking and what you are looking for—for example, "I am checking the tire tread depth to make sure it meets the legal minimum" or "I am checking the brake lines for cracks or leaks."

The examiner is listening to whether you know what to check and why, not whether you can recite a script. You do not need to use exact words, but you do need to show that you understand what each part does and what condition it needs to be in for safe operation. If you point out a defect—a cracked light lens, low tire tread, a loose mirror—you should note it and explain why it matters. The vehicle you bring must be in safe working condition; if it has serious defects, the examiner may not allow you to take the skills test that day.

Most states give you a checklist or a list of items you should cover. Your state's CDL manual includes a sample pre-trip inspection. Many CDL training schools teach the pre-trip inspection as part of their program, and some people memorize a standard order to make sure they do not forget anything.

The behind-the-wheel skills test and what the examiner watches for

The skills test is a driving evaluation that usually lasts 30 to 45 minutes. It has three parts: the pre-trip inspection (covered above), a backing and maneuvering section, and a road driving section. During backing and maneuvering, you perform specific tasks in a controlled area—usually a closed course with cones or marked spaces. Common tasks include straight-line backing, offset backing (backing into a space that is not directly behind you), and alley docking (backing into a narrow space between two obstacles).

During the road driving section, you drive on public roads or a designated test route while the examiner sits in the passenger seat and watches. The examiner will ask you to perform certain actions—merge onto a highway, make a turn, stop at a red light, navigate a roundabout—and will observe whether you do so safely and follow traffic laws. The examiner is looking for smooth steering, appropriate speed, proper use of mirrors, safe following distance, and correct signaling. If you hit a cone during backing, fail to signal a turn, or make an unsafe maneuver, you fail that section.

You must pass all three sections (pre-trip, backing, and road driving) to pass the skills test. If you fail one section, you must retake the entire test, including the sections you passed. Retesting fees vary by state but typically range from $50 to $200 per attempt.

How to prepare and what study materials are available

Your state's CDL manual is the foundation of your preparation. It is free, available online from your state's DMV website, and covers everything on the written tests. Read it carefully, take notes, and review sections you find confusing. Many people read it multiple times before testing.

Practice tests are widely available online, through your state's DMV website, through third-party testing sites, and through CDL training apps. These practice tests use the same format and types of questions as the real exam. Taking practice tests helps you identify weak areas and builds confidence. Some practice tests are free; others cost a small fee.

CDL training schools offer classroom instruction, behind-the-wheel training, and test preparation. A typical program lasts 3 to 8 weeks and costs $3,000 to $8,000, though costs vary widely by location and program length. Training schools can be helpful if you have no commercial driving experience or if you prefer structured instruction, but they are not required. Many people pass the CDL exam by self-studying the manual and practicing with a licensed CDL holder.

For the skills test, practice driving the vehicle you will test in as much as possible. Practice backing, turning, and highway driving. If you can, practice on the same roads or course where the test will take place—many DMVs publish their test routes online or can tell you the general area where testing happens.

Retesting and what happens if you fail

If you fail any part of the exam, you can retake it. If you fail a written test, you can usually retake it the next day or within a few days, depending on your state's policy. If you fail the skills test, you must schedule a new test date; wait times for skills testing vary by state and season, from a few days to several weeks.

Each retake costs a fee. Written test retakes typically cost $10 to $50 per test. Skills test retakes typically cost $50 to $200. If you fail the skills test, you must retake all three sections, even if you passed the pre-trip inspection and backing on your first attempt.

If you fail a written test multiple times, some states limit how many times you can retake it in a certain period, or require you to wait a set number of days between attempts. Check your state's rules before you schedule your first test.

Frequently Asked Questions

Can I use my personal truck for the skills test?

Yes, if it is a commercial vehicle that matches the class of CDL you are testing for. It must be registered as a commercial vehicle, have commercial plates, and be in safe working condition. You cannot use a personal pickup truck registered for personal use, even if you own it.

What happens if I fail the pre-trip inspection?

If you fail the pre-trip inspection, you fail the entire skills test and must retake all three sections. The pre-trip is usually the first part of the test, so failing it means you do not proceed to backing and road driving that day.

Do I need to attend a CDL training school to pass the exam?

No. Many people pass by self-studying the state manual, taking practice tests, and practicing driving with a licensed CDL holder. Training schools are helpful if you have no commercial driving experience or prefer structured instruction, but they are not required by any state.

How many times can I retake the written test?

Most states allow unlimited retakes, but some limit retakes to a certain number per month or require a waiting period between attempts. Check your state's DMV website for the specific rules.

What is the passing score for the CDL written test?

Most states require a score of at least 80 percent on the written tests. Some states use 70 percent. Check your state's DMV website for the exact passing score.