How Many Questions Are on the CDL Test?
TL;DR
There is no single federal number. 49 CFR 383.133 requires each test to contain a set number of questions drawn from prescribed knowledge areas, but leaves the count to your state. What is fixed everywhere is the pass mark: 80% on each knowledge test. Most general knowledge tests run around 50 questions, so 80% usually means about 40 correct.
Why nobody can give you one number
Search this question and you will get confident answers that contradict each other. The reason is that the federal regulations do not set a test length. 49 CFR 383.133 governs how the tests are constructed. It requires that each test contain a set number of questions with a prescribed number of questions from each of the knowledge areas, and it requires the correct answer to sit in a different position and the responses in a different order between versions. What it does not do is name a figure. Your state licensing agency decides how long its test is, working within those federal construction rules. So a driver in one state and a driver in another can both be telling the truth about different numbers.
What is the same everywhere
Two things do not vary, and they matter more than the count. The pass mark is 80% on each knowledge test, set by 49 CFR 383.135. It is per test, not an average across tests. The subject areas are prescribed federally too. Whatever the length, the questions are drawn from defined knowledge areas rather than assembled at random, which is why studying the official manual works regardless of which state you sit in.
- Pass mark: 80% on every knowledge test, nationwide.
- Scored per test, so each endorsement stands on its own.
- Questions drawn from federally prescribed knowledge areas.
- Test length: set by your state.
How many tests will you actually sit?
The count that usually matters more is how many separate tests you face, and that follows from the license you want. Every applicant takes general knowledge. Class A adds combination vehicles. Anyone driving a vehicle with air brakes takes the air brakes test, and skipping it puts a restriction on your license rather than simply leaving a gap. Then each endorsement you want carries its own test: hazmat, tanker, passenger, school bus, doubles and triples. A Class A applicant wanting tanker and hazmat is therefore looking at five separate knowledge tests, each needing 80%.
What to do with this
Stop optimizing for the number and optimize for the margin. Somebody who can hold 90% across a large pool of questions passes whether the test is 50 questions or 30. Somebody sitting at 80% exactly is one unlucky draw from a retake and a fee. Our general knowledge practice tests use a 50-question format, which is the common shape, and every answer comes with an explanation. Use your state page or its licensing agency to confirm the length where you live, then practice well past the line rather than up to it.