The main difference: vehicle weight and passenger capacity

A Class A license lets you drive the heaviest vehicles on the road — tractor-trailers, semi-trucks, and other combinations where the trailer weighs more than 10,000 pounds. A Class B license lets you drive single large vehicles like city buses, dump trucks, and box trucks, but the total weight limit is lower than Class A. The weight thresholds that separate these classes vary slightly by state, but the pattern is the same: Class A handles the biggest rigs, Class B handles large single vehicles.

Both Class A and Class B are called commercial driver's licenses (CDLs), which means they come with stricter rules than a regular passenger license. You need a CDL to drive for pay in a vehicle that crosses certain weight or passenger thresholds. If you drive a personal vehicle under those thresholds, you do not need a CDL — your regular license is fine.

The reason for the distinction matters: a tractor-trailer combination handles completely differently from a single truck. The federal government and states set different training and testing standards for each, because the skills required are not the same.

Key Takeaways

  • Class A licenses cover tractor-trailers and other combinations where the trailer exceeds 10,000 pounds; Class B covers single large vehicles like buses and dump trucks.
  • Both are commercial licenses that require a written test, a skills test, and a medical certificate — more rigorous than a regular driver's license.
  • The weight thresholds that determine which class you need vary by state, so check your state's Department of Motor Vehicles for the exact numbers.
  • You need a CDL only if you drive for pay; personal use of a large vehicle may not require one, depending on weight and your state's rules.
  • Endorsements (like hazmat or passenger) are added to either Class A or Class B and allow you to carry specific cargo or passenger types.

What you can drive with a Class A license

A Class A license covers tractor-trailers, also called semi-trucks or 18-wheelers. It also covers any combination of vehicles where the trailer or towed unit weighs more than 10,000 pounds. This includes doubles (two trailers towed by one tractor) and triples (three trailers). With a Class A, you can also drive anything that requires a Class B license — so the license is a superset.

Most long-haul trucking jobs require a Class A. If you see a truck on the interstate pulling a 53-foot trailer, the driver has a Class A license. You will also see Class A drivers operating specialized equipment like cement mixers on a tractor unit or flatbed trailers carrying heavy machinery.

What you can drive with a Class B license

A Class B license covers single large vehicles — not combinations. This includes city buses, school buses, dump trucks, concrete mixers (the truck itself, not tractor-pulled), box trucks, and garbage trucks. The vehicle itself must weigh more than a certain threshold (usually 26,001 pounds or more, though this varies by state) or be designed to carry more than a certain number of passengers (often 16 or more, including the driver).

Class B is common in local delivery, waste management, public transit, and construction. If you drive a delivery truck around your city or operate a city bus, you likely need a Class B license. You cannot tow a heavy trailer with a Class B — if the trailer weighs more than 10,000 pounds, you need Class A.

How to get a Class A or Class B license

The process is the same for both, though the skills test differs because the vehicles handle differently. First, you must hold a regular driver's license and pass a medical examination by a certified medical examiner. The examiner checks your vision, hearing, blood pressure, and other factors to make sure you can safely operate a large vehicle. This medical certificate is valid for two years.

Next, you take a written knowledge test specific to the class you want. The test covers vehicle operation, safety, cargo handling, and road rules. You study using your state's CDL manual, which is free and available online or at your DMV. Many people take a CDL training course (sometimes called truck driving school) before testing, though it is not required in most states.

Finally, you take a skills test, which includes a pre-trip inspection (you walk around the vehicle and point out safety features), a backing test (you maneuver the vehicle in a controlled space), and a road test (you drive on public roads with an examiner). The road test for Class A involves a tractor-trailer; for Class B, it involves the appropriate single vehicle.

Endorsements: adding permissions to your CDL

Once you have a Class A or Class B license, you can add endorsements — special permissions that let you carry specific types of cargo or passengers. The most common endorsement is Hazmat (H), which allows you to transport hazardous materials like fuel, chemicals, or explosives. To get Hazmat, you pass an additional written test and pass a background check.

Other endorsements include Passenger (P), which is required if you drive a bus with more than 15 passengers; Tanker (N), for vehicles carrying liquids in bulk; and Double/Triple (T), which you need if you tow multiple trailers. Some endorsements require additional testing; others require only paperwork. Your state's DMV can tell you which endorsements are available and what each one requires.

Restrictions that explore to CDL holders

CDL holders face stricter rules than regular drivers. Your blood alcohol limit is 0.04% — half the 0.08% limit for regular drivers — and you cannot use a cell phone while driving except in emergencies. You must report any traffic violations, accidents, or medical changes to your employer and your state within a set timeframe, usually 30 days.

You are also subject to random drug and alcohol testing if you drive for a company. Your CDL can be suspended or revoked for violations like speeding, reckless driving, or driving under the influence. A CDL suspension is separate from a regular license suspension and can last longer.

When you do not need a Class A or Class B license

If you drive a large vehicle for personal use — not for pay — you may not need a CDL, depending on your state and the vehicle's weight. For example, if you own a large RV or a heavy pickup truck and drive it yourself, you typically do not need a CDL. The rule is: you need a CDL if you drive for compensation (pay, including tips) in a vehicle that meets the size or weight threshold.

Some states have exemptions for farmers driving agricultural vehicles, military personnel, or emergency responders. Check your state's DMV website for the exact rules, because they vary.

Frequently Asked Questions

Can I get a Class A and Class B license at the same time?

No. You get one class of CDL, and it is either Class A or Class B. However, a Class A license allows you to drive anything a Class B license allows, so if you have Class A, you do not need a separate Class B. If you only need to drive Class B vehicles, you get Class B.

How long does it take to get a CDL?

The written test can be taken within days of explore. The skills test usually happens within a few weeks, depending on your state's DMV schedule. If you attend a CDL training school first, that adds 3 to 8 weeks. Many people complete the entire process in 4 to 12 weeks.

What happens if I drive a Class A vehicle with only a Class B license?

You can be cited for operating a commercial vehicle without the proper license. The penalty varies by state but usually includes a fine and possible jail time. Your vehicle may be impounded, and your regular license could be suspended.

Do I need a CDL to drive a school bus?

Yes. A school bus requires a Class B CDL and a Passenger (P) endorsement. Some states also require a School Bus (S) endorsement. You must pass the medical exam, written test, and skills test before you can legally operate a school bus.

Can I switch from Class B to Class A later?

Yes. You take the Class A written test and skills test. You do not need to retake the medical exam if your current certificate is still valid. The process is faster than getting your first CDL because you already have the foundational knowledge and experience.