What to Expect on the CDL Test

cdl test infographic

Overview of the CDL Knowledge Test

All drivers of Commercial Motor Vehicles (CMVs) in the United States must possess a Commercial Driver’s License (CDL).  To acquire this specialized license, you must first pass a series of written knowledge tests and earn your Commercial Learner’s Permit (CLP).  The tests are designed to determine if you possess the knowledge to safely operate a commercial vehicle.

Which Tests Should I Take?

The following table summarizes which exams you should take based on the license you plan on obtaining.

License Class General Knowledge Passenger Transport Combination Vehicles Hazardous Materials Tanker Double/Triples Air Brakes
Class A X


If needed If needed If needed


Class B X If needed If needed If needed If needed
Class C X If needed If needed If needed


How Many Questions are on the Test?

You will have to take one or more knowledge tests, depending on what class of license and what endorsements you need.  You will need to answer at least 80% of the questions correctly to pass. The CDL knowledge tests include:

Exam Time Allowed (Minutes) # of Questions on Exam # of Correct Answers Needed to Pass
General Knowledge 60 50 40
Air Brakes 25 25 20
HazMat 30 30 24
Tank 20 20 16
Passenger 20 20 16
Doubles/Triples 20 20 16
Combination Vehicles 20 20 16
School Bus 20 20 16


How Do You Prepare for the Exam?

  • Driver’s Licensing (CDL) Manual – Read your state’s Commercial Driver’s License (CDL Manual).
  • Online Practice Tests – Test your knowledge before scheduling an appointment with online practice tests.

How Much Does it Cost?

Fees vary per state and the type of CDL you are pursuing.  Expect to pay between $5 and $20.

Where Should I Take the Test?

The knowledge tests are written tests that must be taken in your home state.  Contact your local Motor Vehicle Department for information regarding location, associated fees, time allotment, and date of each knowledge test.  Details will vary from state to state.