Class A vs Class B CDL: What Is the Difference?

The difference between a Class A and Class B CDL comes down to one thing: whether you are driving a combination vehicle or a single vehicle. Class A covers tractor-trailers and combination rigs. Class B covers heavy straight trucks, buses, and large delivery vehicles. That single distinction changes which jobs you can take, how much you can earn, and how long your training takes.

This article breaks down every meaningful difference between the two classes — vehicles, weight rules, knowledge tests, pay, jobs, and how to decide which one is right for your situation.

Quick answer: If you want to drive tractor-trailers or 18-wheelers, you need a Class A CDL. If you want to drive straight trucks, buses, or large delivery vehicles without a heavy trailer, a Class B CDL is enough — and faster to get. See CDL Air brakes test explained.

What is a Class A CDL?

A Class A CDL authorizes you to operate any combination of vehicles where the gross combination weight rating (GCWR) exceeds 26,001 pounds, and the towed vehicle — the trailer — weighs more than 10,000 pounds.

In plain language: Class A is the license you need to drive an 18-wheeler, a tractor-trailer, or any rig where a heavy trailer is attached to a heavy truck. It is the most versatile commercial license available, and a Class A holder can legally drive any vehicle covered by Class B or Class C as well. Pass your CDL exam first time.

Class A CDL — What You Can Drive

Combination vehicles over 26,001 lbs GCWR with trailer over 10,000 lbs

• Tractor-trailers (18-wheelers, semi-trucks, big rigs)
• Flatbed trailers pulled by a semi
• Tanker trucks pulling a tanker trailer
• Double and triple trailer combinations (with T endorsement)
• Livestock haulers and refrigerated trailers
• All Class B and Class C vehicles

What is a Class B CDL?

A Class B CDL authorizes you to operate a single vehicle with a gross vehicle weight rating (GVWR) over 26,001 pounds, or to tow a trailer that weighs 10,000 pounds or less.

The key distinction is that word “single.” No heavy trailer attached. A Class B driver operates the entire load in one connected unit — the truck itself carries everything. Think of a city bus, a garbage truck, a large box truck, or a concrete mixer. All of those are Class B vehicles.

Class B CDL — What You Can Drive

Single vehicles over 26,001 lbs GVWR — no heavy trailer attached

• Straight trucks and large box trucks
• City transit buses and coach buses
• School buses (with school bus endorsement)
• Dump trucks and garbage trucks
• Concrete mixer trucks
• Large delivery trucks used by courier services
• All Class C vehicles

Class A vs Class B CDL: side-by-side comparison

Here is every meaningful difference between the two licenses in one place.

The knowledge test difference — what Class A adds

This is the section most comparison articles skip entirely. The knowledge test for Class A and Class B are not identical. Class A requires an extra written test section that Class B does not.

Both classes require the CDL General Knowledge test — 50 questions covering safe driving, vehicle inspection, cargo handling, and driving emergencies. If you want air brakes on either class, you take the Air Brakes knowledge test separately.

What Class A adds on top of that is the Combination Vehicles knowledge test — a separate written section that covers:

• How coupling and uncoupling a trailer works
• How to inspect the fifth wheel and kingpin connection
• Trailer brake systems and how they interact with the tractor
• Rearward amplification and trailer sway on doubles and triples
• Rollover risk on combination vehicles in curves
• Off-tracking — how a trailer’s rear wheels cut inside the tractor’s path on turns

This extra test is not particularly difficult, but it covers concepts that are specific to combination vehicles. If you study only the general knowledge section and show up expecting a Class A permit, you will have a gap in your preparation.

Bottom line on tests: Class B = General Knowledge only (plus endorsements you want). Class A = General Knowledge + Combination Vehicles section (plus endorsements). Budget an extra 3–5 hours of study time for the combination vehicles material if you are going Class A.

Salary: how much more does Class A pay?

Class A drivers earn more on average, but the gap is not as dramatic as CDL schools sometimes suggest. The salary difference depends heavily on the type of route and employer.

The $15,000 average gap between the two classes has a straightforward explanation. Class A drivers are often away from home for days or weeks on over-the-road routes. That time away from home is compensated with higher pay. Class B drivers typically run local routes and are home every night — the tradeoff is a lower base salary.

One thing worth noting: a Class A driver doing local delivery earns similar pay to a Class B driver doing the same type of route. The pay advantage of Class A comes from long-haul and specialized routes — not from the license itself.

Jobs: what each class actually opens up

The job market for Class A is broader, but Class B is not a dead end. Both licenses open stable, well-paying careers with strong demand. The difference is in what types of work are available to each.

One pattern worth noting: most Class B jobs are in municipal services, public transit, and local construction. These jobs tend to offer union contracts, pension benefits, and predictable schedules that many Class A OTR positions do not. If stability and home time matter more than maximum earning potential, Class B jobs often win that comparison.

Can you upgrade from Class B to Class A?

Yes — and this is an important option that most comparison articles do not mention. If you start with a Class B CDL and later want to upgrade to Class A, you do not start from scratch.

To upgrade from Class B to Class A you need to:

1. Pass the Combination Vehicles knowledge test at your state DMV
2. Complete ELDT training on a combination vehicle from an FMCSA-registered provider
3. Pass the Class A skills test in a tractor-trailer

You do not need to retake the general knowledge test, and any endorsements you already hold stay on your license. The upgrade path typically takes 2 to 3 weeks of additional training.

This is useful to know if your current job only requires Class B but you want to keep your options open. Getting Class B first and upgrading later is a legitimate strategy — especially if your employer will pay for the upgrade training after you have proven yourself on the job.

Upgrade path tip: Some large carriers — UPS, FedEx, Amazon DSP — hire drivers with Class B CDLs for delivery routes and then sponsor the Class A upgrade. If cost is a barrier to Class A training, starting at Class B and letting an employer sponsor the upgrade is a real option worth researching.

Which one should you get?

This is the question everyone arrives at, and most articles answer it vaguely. Here is a direct framework based on your actual situation.

What about Class C?

Class C covers vehicles under 26,001 lbs that either transport 16 or more passengers, or carry hazardous materials that require placarding. It is a narrower license than B or A and is typically required for passenger vans, small para-transit vehicles, and certain hazmat delivery roles.

Most people asking about Class A vs Class B are not looking at Class C, but it is worth knowing that both Class A and Class B automatically cover everything in Class C — so if you have either of the two main licenses, Class C is already included.

Preparing for the CDL knowledge test

Whichever class you choose, the path starts the same way: study the FMCSA CDL manual, pass the written knowledge test at your state DMV, and get your Commercial Learner Permit. Only then can you start behind-the-wheel training.

The general knowledge test is the same for both Class A and Class B. Class A adds the combination vehicles section on top. If you are going Class A, study both sections before your DMV visit so you can pass both tests in one trip and get your CLP without delay.

Air brakes is another section worth studying before school. Most Class A and many Class B vehicles have air brake systems. If you do not pass the air brakes knowledge test, your license comes with an air brakes restriction — meaning you cannot legally drive any vehicle with air brakes until you remove it. That restriction costs you job opportunities from day one.