A Class B CDL is for drivers of medium-duty trucks and buses

A Class B Commercial Driver's License authorizes you to operate single vehicles with a gross vehicle weight rating (GVWR) between 26,001 and 33,000 pounds. The key difference from a Class A is that a Class B covers vehicles you will drive alone — not tractor-trailers or combinations where you tow a trailer weighing more than 10,000 pounds.

The vehicles you can legally drive with a Class B include straight trucks (box trucks, dump trucks, cement mixers), city buses, school buses, and some delivery trucks. You cannot drive a tractor pulling a trailer, even if the total weight would otherwise fall within Class B limits. If the trailer weighs more than 10,000 pounds, you need a Class A instead.

Class B requirements and restrictions vary by state, but the federal baseline is consistent: you must pass a written knowledge test covering air brakes, combination vehicles (even though you cannot drive combinations), and general commercial driving rules. You also must pass a skills test — pre-trip inspection, basic control, and an on-road driving exam — in the specific vehicle category you want to drive.

Key Takeaways

  • A Class B CDL covers single vehicles weighing 26,001 to 33,000 pounds, such as straight trucks and buses, but not tractor-trailers.
  • You must pass a written knowledge test and a three-part skills test (pre-trip, basic control, on-road) in the vehicle type you intend to drive.
  • Endorsements — such as air brakes, passenger, or hazmat — are added to your Class B and each requires a separate test.
  • Most states require you to hold a valid regular driver's license before you can obtain a Class B CDL.
  • Medical certification through a Department of Transportation physical is mandatory and must be renewed every two years.

Vehicle categories and weight limits for Class B

The 26,001 to 33,000-pound range covers the majority of commercial trucks you see on local roads. A typical straight truck — the kind used for local delivery, refuse collection, or moving — falls into this category. So do most city transit buses and school buses, which is why school bus drivers in most states hold a Class B with a passenger endorsement.

The upper boundary matters because it determines whether you need a Class A. If you drive a tractor pulling a trailer, the combined GVWR of the tractor and trailer must be calculated together. If that total exceeds 26,001 pounds and the trailer weighs more than 10,000 pounds, you need a Class A, not a Class B. A Class B does not permit you to tow any trailer heavier than 10,000 pounds, regardless of the tractor's weight.

Some states also recognize a Class C CDL for smaller commercial vehicles (between 16,001 and 26,000 pounds), but Class B is the most common intermediate tier. Your state's DMV website lists the exact vehicle types and weights that fall under each class.

Written and skills tests required for Class B

Before you take the skills test, you must pass the written knowledge exam. The test covers general commercial driving rules, vehicle inspection, safe driving practices, and air brake operation. Even though Class B drivers do not operate combination vehicles, the test includes questions about combination vehicles — federal rules require this for all CDL classes.

The skills test has three parts, all conducted in the actual vehicle you plan to drive. First is the pre-trip inspection, where you walk around and point out safety features, fluid levels, lights, and brake condition. Second is the basic control test, performed in a closed course, where you demonstrate backing, turning, and parking. Third is the on-road test, where an examiner rides with you on public roads and evaluates your steering, braking, lane changes, and overall safety.

You must pass all three parts on the same day to pass the skills test. If you fail one section, you typically must retake the entire test, though some states allow you to retake only the failed portion. Scheduling the test can take weeks in busy areas, so plan ahead.

Endorsements that add to a Class B CDL

An endorsement is a notation on your CDL that permits you to drive or transport specific cargo or passenger types. The most common endorsements for Class B drivers are:

  • Passenger (P) — required to drive buses carrying 16 or more people, including school buses.
  • Air Brake (X) — required if the vehicle has air brakes; you cannot drive air-brake vehicles without this endorsement.
  • Hazmat (H) — required to transport hazardous materials; involves a background check and TSA clearance.
  • Tank (N) — required to drive tanker trucks carrying liquids or gases.

Each endorsement requires a separate written test. If you drive a school bus with air brakes, you need both the P and X endorsements. The hazmat endorsement also requires fingerprinting and a background check through the Transportation Security Administration (TSA), which can take several weeks.

Medical certification and renewal requirements

To obtain or renew a Class B CDL, you must pass a Department of Transportation (DOT) medical examination performed by a certified medical examiner. The exam checks your vision, hearing, blood pressure, and overall health. You cannot have certain conditions — such as uncontrolled diabetes, heart disease, or sleep apnea — without a waiver from the Federal Motor Carrier Safety Administration (FMCSA).

The medical certificate is valid for two years from the date of the exam. Your CDL itself may be valid for longer (typically four to eight years depending on your state), but you cannot legally drive commercially after your medical certificate expires. You must renew the medical certificate before it expires; driving after expiration can result in fines and loss of your CDL.

Some states allow you to renew your medical certificate at the same time you renew your CDL. Others require a separate visit to a medical examiner. Check your state's DMV website for the renewal timeline and process.

Class B versus Class A: what changes

The main difference is vehicle weight and configuration. A Class A permits you to drive any single vehicle or combination (tractor plus trailer) as long as the combination weighs more than 26,001 pounds. A Class B limits you to single vehicles in the 26,001 to 33,000-pound range and does not permit tractor-trailer combinations.

The written test is the same for both classes — both cover combination vehicles even though Class B drivers cannot operate them. The skills test, however, is performed in the vehicle type you will actually drive. If you take the Class B skills test in a straight truck, you are certified only for straight trucks; you cannot then drive a bus without taking the skills test again in a bus.

Some drivers obtain a Class B first, then upgrade to a Class A later if their job changes. The upgrade typically requires only the skills test in a combination vehicle; you do not retake the written exam. Your state's DMV can explain the upgrade process and any fees involved.

State-specific rules and variations

While federal law sets the baseline for CDL classes, each state administers its own licensing and testing. Some states have additional endorsements or restrictions not found in others. For example, a few states require a separate endorsement for doubles or triples (multiple trailers), while others include this under the Class A definition.

Age requirements also vary. Most states allow you to obtain a Class B at age 18 for intrastate driving (within your state) and age 21 for interstate driving (across state lines). Some states have different rules for school bus drivers or hazmat endorsements.

Your state's DMV website lists the specific vehicle types, weight limits, endorsements, and testing procedures for your state. If you are moving to a new state, you may need to retake the skills test even if you already hold a Class B, because testing standards can differ.

Frequently Asked Questions

Can I drive a school bus with a Class B CDL?

Yes, if you have the passenger (P) endorsement. School buses fall within the Class B weight range. You must pass the passenger endorsement test, which covers passenger safety, emergency procedures, and student management. Some states also require a separate school bus endorsement with additional training.

Do I need air brake certification if my truck has air brakes?

Yes. If the vehicle has air brakes, you must have the air brake (X) endorsement. If you take your skills test in a vehicle without air brakes, you will receive a restriction on your CDL that prohibits you from driving air-brake vehicles. You can remove this restriction by passing the air brake test in a vehicle with air brakes.

What happens if my medical certificate expires?

You cannot legally drive a commercial vehicle once your medical certificate expires. Your CDL remains valid, but it is not usable for commercial driving. You must renew your medical certificate before you can resume driving. Driving with an expired medical certificate can result in fines and suspension of your CDL.

Can I upgrade from Class B to Class A without retaking the written test?

Yes, most states allow you to upgrade by taking only the skills test in a combination vehicle. You do not retake the written exam. However, you must still pass the three-part skills test (pre-trip, basic control, on-road) in a tractor-trailer. Contact your state's DMV for the specific upgrade process and any fees.

What disqualifies me from getting a Class B CDL?

Serious traffic violations, DUI convictions, reckless driving, and certain felonies can disqualify you or result in a lengthy waiting period. Medical conditions such as uncontrolled diabetes, heart disease, or untreated sleep apnea also disqualify you unless you obtain a waiver from the FMCSA. Your state's DMV can tell you whether a specific conviction or condition affects your may be able to access.