How many questions are on the CDL permit test?
It depends on the test and on your state, which sets the count. The General Knowledge test, which every CDL applicant takes, has 50 questions in Utah. Air Brakes has 25, Combination Vehicles 20 and Hazmat 30, going by the Utah and Michigan pages. Federal rules require 80 percent correct on each test, so 40 of 50 on General Knowledge.
In more detail
The CDL (Commercial Driver's License) is the US license for heavy commercial vehicles, and the commercial learner's permit (CLP) comes from passing the written tests. It is not one test: the CLP needs the tests that match your license class and the endorsements you want, and each is scored on its own. Everyone takes General Knowledge. Class A applicants add Combination Vehicles, and anyone who will drive a truck with air brakes adds Air Brakes.
Each state sets its own counts, so check your state's DMV page and handbook. Utah lists 50 questions for General Knowledge, 25 for Air Brakes and 20 for Combination. Michigan lists 50 for Group B and C, 70 for Group A plus a separate 20-question Combination test, 20 each for Passenger, School Bus, Tank and Doubles/Triples, and 30 for Hazmat.
The pass mark is federal: under 49 CFR 383.135 you must answer at least 80 percent of the questions correctly on each knowledge test. Fail Air Brakes and your license gets an air brake restriction; fail Combination and you cannot get a Class A. It is not the same as a car permit test: it is closed book, multiple choice and covers heavier topics such as air brakes, cargo and pre-trip inspection.
CDL knowledge tests (Utah DLD and Michigan SOS, October 2026)
| Test | Questions | Correct to pass (80%) | Who takes it |
|---|---|---|---|
| General Knowledge | 50 | 40 | Every Class A, B or C applicant |
| Air Brakes | 25 | 20 | Anyone who will drive a truck with air brakes |
| Combination Vehicles | 20 | 16 | Class A applicants |
| Hazmat (H) | 30 | 24 | Drivers carrying placarded hazardous materials |
| Passenger (P) | 20 | 16 | Drivers of vehicles for 16 or more people |
| School Bus (S) | 20 | 16 | School bus drivers |
| Tank Vehicle (N) | 20 | 16 | Drivers of tank vehicles |
| Doubles/Triples (T) | 20 | 16 | Drivers pulling double or triple trailers |
Step by step
- 1
Check your state's CDL page for the tests your class and endorsements need and how many questions each has.
- 2
Work out the correct answers you need: 80 percent of each test, so 40 of 50, 20 of 25, 16 of 20 or 24 of 30.
- 3
Study General Knowledge first, because every class needs it, then Combination or Air Brakes if they apply to you.
- 4
Take a timed practice test per subject from your state's handbook and review every miss until you can explain the right answer.
- 5
Book the written tests once you score at least 80 percent on practice tests in every subject you need.
How StudyPDF helps
Passing means knowing your state's handbook, not guessing. Upload the handbook chapters and your own notes and StudyPDF builds flashcards, quizzes and practice exams from them, each answer linked to the page it came from. Your mastery per concept shows which topics, such as air brakes or cargo, still cost you points, so the next quiz goes after them.
See also
Do it on your own course
Upload your lectures and ask Bo. Cited answers, plus flashcards, exams, and more built from your material.
More questions
What score do you need to pass the CDL permit test?
At least 80 percent on each knowledge test, which is a federal rule (49 CFR 383.135). That is 40 of 50 on General Knowledge and 20 of 25 on Air Brakes.
Is the CDL permit test harder than the car permit test?
It has several tests instead of one and covers heavier topics such as air brakes, cargo and pre-trip inspection. Each test is closed book and multiple choice, and each needs 80 percent.