The four CDL classes and what vehicles each one covers

A Commercial Driver's License (CDL) comes in three classes — A, B, and C — and each one permits you to operate different categories of heavy or commercial vehicles. The class you need depends on the vehicle's Gross Vehicle Weight Rating (GVWR), which is the maximum weight the vehicle can safely carry including cargo and passengers. Your state's DMV determines which class applies to any specific truck or bus you want to drive.

Class A is the broadest CDL. It covers any combination of vehicles with a GVWR of 26,001 pounds or more, as long as the towed vehicle weighs more than 10,000 pounds. This includes tractor-trailers, doubles, and triples. Class A also covers any single vehicle with a GVWR of 26,001 pounds or more, and any Class B or Class C vehicle.

Class B covers single vehicles with a GVWR of 26,001 pounds or more that are not towing anything, or towing a vehicle under 10,000 pounds. This includes straight trucks, large buses, and dump trucks. A Class B license does not permit you to operate Class A vehicles.

Class C is the most limited CDL. It covers vehicles that do not meet Class A or B weight thresholds but still require a CDL because of what they carry — typically passenger vehicles like buses or vans carrying 16 or more people, or any vehicle carrying hazardous materials. Class C drivers cannot operate Class A or B vehicles.

Key Takeaways

  • Class A CDL covers tractor-trailers and any combination vehicle where the towed unit weighs over 10,000 pounds, and is the most versatile commercial license.
  • Class B CDL covers single heavy trucks and buses but not towing operations, making it suitable for straight-truck driving and local delivery routes.
  • Class C CDL applies to vehicles carrying 16 or more passengers or hazardous materials, even if they fall below the weight thresholds of Class A or B.
  • Your state's DMV determines which class you need based on the vehicle's GVWR and what it carries, not your choice.
  • Endorsements and restrictions can be added to any CDL class to permit or restrict specific operations like hazmat transport or passenger carrying.

Endorsements that modify what you can haul or carry

Beyond the three classes, a CDL can carry endorsements — special permissions that allow you to operate vehicles or carry cargo that would otherwise be off-limits. You request endorsements when you test for your CDL, and each one requires passing a written exam on top of the general knowledge test.

The H endorsement (hazardous materials) permits you to transport hazmat cargo. This is the most common endorsement and requires passing the hazmat knowledge test and a background check. Without an H endorsement, you cannot legally haul hazmat loads even if your vehicle is equipped for it.

The P endorsement (passenger) allows you to operate vehicles designed to carry 16 or more passengers. School bus drivers and charter bus operators need this endorsement. The test covers passenger safety, loading procedures, and emergency protocols.

The T endorsement (double/triple trailers) permits you to tow double or triple trailers. This endorsement is only available to Class A CDL holders and requires demonstrating knowledge of coupling procedures and weight distribution.

The N endorsement (tank vehicles) covers tanker trucks carrying liquids or gases. Tank vehicles have different handling characteristics than dry vans, and the test covers load shifting, braking, and safe operation of pressurized or baffled tanks.

The S endorsement (school bus) is specific to drivers operating school buses and includes additional safety and student management requirements beyond the P endorsement.

Restrictions that limit how you can drive

Restrictions are the opposite of endorsements — they limit what you can do with your CDL. Your state may place restrictions on your license based on your medical status, test performance, or vehicle type. Common restrictions include air brake restrictions, automatic transmission restrictions, and restrictions on certain vehicle types.

An air brake restriction means you cannot operate vehicles equipped with air brakes. If you pass your CDL test in a vehicle with automatic or manual transmission brakes, your license may carry this restriction. You can remove it by passing an air brake knowledge test and a skills test in a vehicle with air brakes.

An automatic transmission restriction means you can only drive vehicles with automatic transmissions. This restriction applies if you test in an automatic vehicle. Removing it requires retesting in a manual transmission vehicle.

Some states impose vehicle-specific restrictions — for example, limiting you to straight trucks only, or prohibiting doubles and triples. These are usually temporary and can be removed by passing additional skills tests.

How to determine which class you actually need

The vehicle's GVWR is the deciding factor, not the vehicle's current weight or what you plan to carry on a given day. GVWR is a fixed specification set by the manufacturer and appears on a placard on the driver's side door jamb. If the GVWR is 26,001 pounds or more, you need a CDL of some class.

If you are unsure whether a specific vehicle requires a CDL, check the GVWR first. Then ask yourself: am I towing anything? If yes, does the towed vehicle weigh more than 10,000 pounds? If yes to both, you need a Class A. If you are not towing, or towing something under 10,000 pounds, you need a Class B. If the vehicle is under 26,001 GVWR but carries 16+ passengers or hazmat, you need a Class C.

Your employer or the vehicle owner can also tell you which class is required — they are legally responsible for ensuring drivers have the correct license. If you are unsure, ask before you start driving.

Testing requirements vary by class and endorsement

Every CDL requires passing a general knowledge test covering traffic laws, vehicle inspection, and safe driving practices. Class A, B, and C each have their own knowledge test. On top of that, you must pass a skills test — a pre-trip inspection, a basic control test, and a road test — in a vehicle of the class you are seeking.

Each endorsement requires an additional knowledge test. If you want both an H endorsement (hazmat) and a P endorsement (passenger), you take two extra tests beyond the class test. Some states allow you to take all tests in one visit; others require spacing them out.

Restrictions are usually applied based on the vehicle you test in or your medical certification status, not a separate test. If you want to remove a restriction, you typically take a knowledge test and a skills test specific to that restriction.

Medical certification and CDL validity

All CDL holders must pass a Department of Transportation (DOT) medical examination conducted by a certified medical examiner. The exam checks vision, hearing, blood pressure, and other health factors. You receive a Medical Certificate (also called a Medical Examiner's Certificate) that is valid for up to two years.

Your CDL is only valid while your Medical Certificate is current. If your Medical Certificate expires, your CDL becomes invalid even if the license card itself has not expired. You must renew the Medical Certificate before you can legally drive a commercial vehicle.

Some drivers receive a Restricted Medical Certificate if they have a condition that requires monitoring — for example, diabetes or sleep apnea. A Restricted Medical Certificate may be valid for only one year instead of two, and may come with additional requirements like more frequent check-ups.

Frequently Asked Questions

Can I upgrade from Class B to Class A without retesting?

No. You must pass the Class A knowledge test and a skills test in a Class A vehicle. Some states allow you to take both tests on the same day. The process is called upgrading, but it requires the full testing sequence.

Do I need an endorsement to drive a dump truck?

Only if the dump truck's GVWR is 26,001 pounds or more — then you need a Class B CDL. You do not need an endorsement for the dump truck itself, but if it carries hazmat (like certain fuels or chemicals), you need an H endorsement.

What happens if I let my Medical Certificate expire?

Your CDL becomes invalid when ready. You cannot legally operate a commercial vehicle until you renew your Medical Certificate with a DOT medical examiner. Your license card remains valid, but it is not usable for commercial driving.

Can I have multiple endorsements on one CDL?

Yes. You can hold H, P, T, N, and S endorsements all on the same license, as long as you pass the knowledge test for each one and meet any other state requirements. Your license card will list all active endorsements.

Is a Class C CDL harder to get than Class A?

No — Class C has a simpler knowledge test and no skills test in most states. The difficulty depends on the endorsements you add. A Class C with an H endorsement (hazmat) requires passing the hazmat test, which many drivers find challenging.