The difference between Class A and Class B licenses

A Class A license lets you drive the largest vehicles on the road: tractor-trailers, semi-trucks, and any combination of vehicles where the trailer weighs more than 10,000 pounds. A Class B license covers single large vehicles like straight trucks, buses, and dump trucks — but not combinations where a trailer is involved. The key distinction is that Class A requires you to handle a towed unit, while Class B is for one vehicle only, no matter how heavy.

Both are commercial licenses, meaning you need them to drive for pay or to operate vehicles above certain weight thresholds. If you currently have a regular passenger license (usually called Class C or Class D depending on your state), you cannot legally drive a Class A or Class B vehicle for any purpose — commercial or personal — without upgrading first.

The weight threshold that triggers the need for a commercial license varies slightly by state, but federal law sets the baseline at 26,001 pounds or more for the vehicle itself, or 10,001 pounds or more if you are towing a trailer. Some states have lower thresholds for certain vehicle types.

Key Takeaways

  • Class A licenses cover tractor-trailers and any vehicle combination where the trailer weighs over 10,000 pounds; Class B covers single large vehicles like buses and straight trucks.
  • You cannot legally drive a Class A or Class B vehicle with a regular passenger license, even if you own the vehicle.
  • Both require a written knowledge test, a skills test with an actual vehicle, and a medical examination before you can obtain them.
  • Class A requires more training and testing than Class B because tractor-trailers are more complex to operate and more dangerous on the road.

What vehicles fall under Class A

Class A covers any combination of vehicles where the towed unit (trailer) has a gross vehicle weight rating (GVWR) of more than 10,000 pounds. This includes standard 18-wheeler tractor-trailers, flatbed trailers carrying heavy equipment, tanker trucks hauling liquids, and refrigerated trailers. It also covers doubles and triples — two or three trailers pulled by one tractor — which are common in long-haul trucking.

The tractor unit itself can be any size; what matters is the weight of what you are pulling. A small tractor pulling a 15,000-pound trailer still requires a Class A license. Conversely, a massive tractor pulling a light trailer under 10,000 pounds would not require Class A — though in practice, tractors are almost always paired with heavy trailers.

Class A is the highest commercial license tier in every state. If you hold a Class A, you can legally drive any Class B vehicle as well, but not the reverse.

What vehicles fall under Class B

Class B covers single vehicles with a GVWR of 26,001 pounds or more that are not towing anything. The most common Class B vehicles are city transit buses, school buses, straight trucks (dump trucks, box trucks, cement mixers), and large delivery trucks. A dump truck carrying a full load of gravel is Class B. A box truck used by a moving company is Class B. A city bus is Class B.

The defining feature is that you are operating one vehicle, not a combination. If that single vehicle weighs more than 26,001 pounds, you need a Class B license. Some states also require Class B for smaller vehicles in certain categories — for example, some states require it for any bus carrying passengers, regardless of weight.

Class B is easier to obtain than Class A because the vehicle is simpler to maneuver and you do not have to manage a trailer. The testing is less rigorous, and the training period is typically shorter.

Medical certification and health requirements

Before you can obtain either a Class A or Class B license, you must pass a Department of Transportation (DOT) medical examination. This is not the same as a regular eye exam or physical. A certified medical examiner — usually a doctor, nurse practitioner, or physician assistant — will check your vision, hearing, blood pressure, and ability to operate a vehicle safely.

You will be disqualified if you have certain conditions: uncontrolled diabetes, heart disease, sleep apnea that is not being treated, or a history of seizures. You may also be disqualified if you take medications that impair judgment or reaction time. The examiner will give you a list of conditions to disclose on the form before the exam.

If you pass, you receive a Medical Certificate (also called a Medical Examiner's Certificate or MEC). This certificate is valid for two years in most cases, though some conditions require annual renewal. You must carry this certificate with you whenever you drive a commercial vehicle, and you must renew it before it expires or you lose your right to drive commercially.

Written test and knowledge requirements

Both Class A and Class B require you to pass a written knowledge test specific to commercial driving. The test covers federal and state regulations, vehicle inspection procedures, safe driving practices, and how to handle emergencies. You will be tested on topics like proper braking distance, how to inspect your vehicle before driving, what to do if your brakes fail, and how to find cargo.

Class A testing is more extensive because you must know how to handle a tractor-trailer combination. You will be asked about coupling and uncoupling procedures, how weight distribution affects handling, and how to back up a trailer safely. Class B testing focuses on the single vehicle you will be operating but still covers all the federal safety rules.

Most states allow you to take the written test at the DMV or a testing center. You can study using the state's commercial driver handbook, which is free and available online. Many people also use third-party study guides or practice tests to prepare. You typically get one or two chances to pass; if you fail, you wait a set period (often 7 days) before retesting.

Skills test and behind-the-wheel evaluation

After you pass the written test, you must take a practical skills test with an actual vehicle. This test has three parts: a pre-trip vehicle inspection, a basic control skills test, and an on-road driving test. You must bring a vehicle that matches the class you are testing for — you cannot test for Class A in a car or a Class B vehicle.

The pre-trip inspection requires you to walk around the vehicle and point out safety features, check fluid levels, test the brakes, and demonstrate that you know how the vehicle works. The examiner will ask you to show where the fire extinguisher is, how to check tire pressure, and how to inspect lights and mirrors. This part tests whether you can spot problems before they become dangerous.

The basic control skills test takes place in a closed course or parking lot. You will be asked to back up in a straight line, back into a dock or alley, and perform other maneuvers that show you can control the vehicle precisely. For Class A, this includes coupling and uncoupling the trailer. For Class B, it focuses on tight turns and backing in confined spaces.

The on-road test lasts 30 minutes to an hour. You drive on public roads while the examiner watches and scores your performance. You must follow traffic laws, make smooth turns, maintain safe speed, and respond correctly to traffic signals and other vehicles. Any major safety violation — running a red light, unsafe lane change, or hitting something — results in automatic failure.

Training and preparation before testing

You are not legally required to attend a commercial driving school before testing, but most people do because the failure rate for unprepared applicants is high. A typical commercial driving school program lasts 3 to 7 weeks and covers classroom instruction, vehicle inspection training, and 100 to 200 hours of behind-the-wheel practice with an instructor.

If you choose to study on your own, you will need access to a suitable vehicle for practice — which is difficult for most people because they do not own a tractor-trailer or large truck. You will also need to arrange for someone with a valid Class A or Class B license to supervise your practice driving in most states. This is why schools are so common: they provide the vehicle and the experienced instructor.

Some employers, particularly trucking companies, will pay for your training if you agree to work for them for a set period after you obtain your license. This is a common entry point for people without prior commercial driving experience. Others pay out of pocket, which typically costs $3,000 to $7,000 depending on the school and program length.

Frequently Asked Questions

Can I drive a Class B vehicle with a Class A license?

Yes. A Class A license is the highest tier, so it covers everything Class B covers. If you hold Class A, you can legally drive any Class B vehicle. The reverse is not true — Class B does not permit you to drive Class A vehicles.

What happens if I drive a Class A or Class B vehicle without the proper license?

You can be cited for operating a commercial vehicle without a commercial license, which is a serious violation. Penalties include fines (often $500 to $1,000 or more), points on your record, and possible jail time depending on your state. Your vehicle may also be impounded. If you cause an accident while driving illegally, your insurance may not cover it.

Do I need a Class A or Class B license to drive my own truck?

Yes, if the vehicle meets the weight threshold. It does not matter whether you own it, are borrowing it, or are driving it for work. If it is a Class A or Class B vehicle by weight and configuration, you must have the corresponding license to operate it legally on public roads.

How long does it take to get a Class A or Class B license?

If you attend a commercial driving school, the process typically takes 3 to 7 weeks from start to finish. If you study on your own, it depends on how quickly you can schedule the written test and skills test with your state's DMV, which can range from a few weeks to several months. The actual testing day takes a few hours.

Can I get a Class A or Class B license if I have a DUI or traffic violations on my record?

It depends on the violation and your state's rules. Most states allow you to obtain a commercial license even with a DUI or traffic violations, but some violations may disqualify you or require a waiting period. Check with your state's DMV or a commercial driving school to understand your specific situation.