How many questions are on the CDL test?
Fifty on general knowledge, 20 to 30 on each endorsement test, and you can miss one in five. The count for every test, in one place.
The CDL knowledge tests follow a federal model, so the numbers are nearly the same wherever you take them. The general knowledge test has 50 questions. Every other knowledge test has between 20 and 30. The passing score is 80% on each one, so you can miss one question in five.
Question count for every CDL test
| Test | Questions | Correct to pass (80%) | Who takes it |
|---|---|---|---|
| General knowledge | 50 | 40 | Everyone |
| Air brakes | 25 | 20 | Anyone who will drive a vehicle with air brakes |
| Combination vehicles | 20 | 16 | Class A applicants |
| Hazardous materials | 30 | 24 | H and X endorsement |
| Tanker | 20 | 16 | N and X endorsement |
| Doubles and triples | 20 | 16 | T endorsement |
| Passenger | 20 | 16 | P endorsement |
| School bus | 20 | 16 | S endorsement |
These are the counts in the model tests that the Federal Motor Carrier Safety Administration (FMCSA) and the American Association of Motor Vehicle Administrators publish for the states. Most states use them as they are. A few states build their own versions with a different count, and a few set a higher pass mark for one test. Your state page shows anything the state's own licensing agency says about this.
How many tests you actually take
Nobody takes all eight. The set depends on the licence class and the endorsements you want:
- Class A (tractor-trailer): general knowledge, combination vehicles, and air brakes if the truck has them. That is 95 questions in one sitting if you take them all at once.
- Class B (straight truck, dump truck, city bus): general knowledge and air brakes. 75 questions.
- Class C (small vehicles that carry 16 or more people or placarded hazmat): general knowledge plus the passenger or hazmat test.
- Endorsements add their own test each. A driver going for tanker and hazmat together can take one combined X endorsement, but still sits both knowledge tests.
The Class A, B and C guide explains which class you need. The endorsements guide covers the letters.
What the questions look like
Every question is multiple choice, usually with three or four answers. They are written from the CDL manual: Section 2 for general knowledge, Section 5 for air brakes, Section 6 for combination vehicles, and Sections 7 to 10 for the endorsements. Most questions ask for a rule, a number or a procedure straight from the text. The manual says the low air pressure warning must come on before pressure drops below 55 psi, so a question asks at what pressure the warning comes on.
Most states give the test on a computer at the licensing office. There is usually no strict time limit, though some states say you must start well before closing time. You see one question at a time and can skip and come back in most systems.
Can you take all the tests on the same day?
In most states, yes, as long as you pay for them and the office has time. Many drivers take general knowledge first, then come back for the others once they have passed it. If you fail one test, the ones you passed normally stay valid, so you only retake the one you missed. The failed test guide has the waiting rules by state.