Who takes it
The general knowledge test is the one test every CDL applicant shares. To get a commercial learner's permit (CLP), federal rules say you must be at least 18 and have passed a general knowledge test for the vehicle group you will drive. California's handbook puts it plainly: the general knowledge test is required to be taken by all applicants, whether you want Class A, B or C.
Our CDL practice test page covers the whole permit process, fees and the medical card. This guide is only about the general knowledge test: its length, its scoring and what is on it.
How many questions are on the CDL permit test?
There is no single national number. Federal rules require each state to build its tests from an FMCSA pre-approved pool of questions, with "a set number of questions with a prescribed number of questions from each of the knowledge areas", but the number itself appears on state pages, not in the regulation. Here is what the states we checked publish:
| State | General knowledge | Air brakes | Combination | Notes |
|---|---|---|---|---|
| Washington | 50 (40 to pass) | 25 (20) | 20 (16) | English, Spanish, Russian, Serbian-Croatian |
| Utah | 50 | 25 | 20 | Closed book, multiple choice, English only |
| New York | Not stated in the manual | Not stated | Not stated | One correct answer from three choices |
| California | Not stated in the handbook | Not stated | Not stated | Six languages, on automated testing equipment |
So in these two states "the CDL permit test" can mean 50 questions or 95. A Class A applicant in Washington who takes general knowledge, air brakes and combination answers 50 + 25 + 20 questions, and each test is scored on its own.
California lists its knowledge tests in English, Arabic, Chinese, Punjabi, Russian and Spanish, given on its automated testing equipment, and tells you to allow 2 to 3 hours if taking all tests. New York's manual says to allow three hours for all the processing, test-taking included, and to arrive no later than three hours before closing.
The 80% rule
Federal rules require you to answer at least 80 percent of the questions correctly on each knowledge test. With the lengths above:
| Questions | Correct answers needed | Misses allowed |
|---|---|---|
| 50 | 40 | 10 |
| 25 | 20 | 5 |
| 20 | 16 | 4 |
The same rule explains what happens if one test goes badly. Fail air brakes and the permit can still be issued, but with an air brake restriction. Fail combination vehicles and the state must not issue a Class A permit or license. Fail general knowledge and there is no permit at all.
Why two attempts never look the same
The federal test method rules are strict about versions (49 CFR 383.133):
- 25% of the questions on a test must be new compared with the previous version.
- Questions kept from the previous version must sit in a different place, with the three answers in a different order.
- If you retake a test you failed, the state must use a different version.
Memorizing answer positions from a first attempt is useless. What carries over is knowing the rule behind each question. Retake limits are a state matter: California gives three attempts at each required knowledge test, after which the application is no longer valid, while New York says there is no limit, at the discretion of the office.
What the general knowledge test covers
Federal rules list 20 general knowledge areas every commercial driver must know: safe operations regulations, vehicle controls, safety systems, basic control, shifting, backing, visual search, communication, speed management, space management, night operation, extreme driving conditions, hazard perception, emergency maneuvers, skid control and recovery, cargo and vehicle control, vehicle inspections, hazardous materials, mountain driving, and fatigue and awareness.
The state manuals turn that list into chapters. In the California handbook, Section 2 "Driving Safely" runs from vehicle inspection, basic control, shifting, seeing, communicating, speed and space management, through distracted and aggressive driving, night, fog, winter and hot weather, railroad crossings, mountain driving, emergencies, ABS, skids, crashes and fires, to alcohol and drugs and the hazardous materials rules all drivers must know. Section 3 covers cargo: inspecting it, weight and balance, and securing it.
New York tells general knowledge candidates to study Sections 1, 2, 3, 11, 12 and 13: the introduction (licensing rules), driving safely, transporting cargo, and the three skills test sections. Vehicle inspection is also one of the 20 federal knowledge areas, so expect inspection questions. Our pre-trip inspection guide walks through what those sections ask you to check.
Which other tests you need
The general knowledge test is only the first one for most applicants. California's handbook lists the others and when each is required:
| You plan to drive | Add this test |
|---|---|
| A vehicle with air brakes, including air over hydraulic | Air brakes |
| A combination vehicle (Class A) | Combination vehicles |
| A bus | Passenger transport |
| Double or triple trailers | Doubles/triples |
| A tank vehicle | Tank vehicle |
| Placarded hazardous materials | Hazardous materials |
| A school bus | School bus |
How the classes differ is covered in Class A vs Class B, the endorsement tests in CDL endorsements, and the brake test in the CDL air brakes test. Training is not required before the general knowledge test, but it is before the skills test for a first Class A or B license: see entry-level driver training.
After you pass
Passing gets you the CLP, not the CDL. Federally, a CLP is valid for no more than one year from first issue, and you cannot take the skills test in the first 14 days. Some states set shorter clocks: Washington says knowledge test scores are valid for 180 days, extended by another 180 days if you renew the CLP within 30 days of expiration.
How to prepare
Get your state's CDL manual from its DMV website and read Sections 1 to 3 first (the section numbers above are California's and New York's; check your own manual's table). Answer the review questions at the end of each subsection; both the California and New York manuals note that such questions may be on your test. Then practice under realistic conditions: one sitting, no notes, and score yourself against the 80% line. Our general knowledge practice questions are original, written from the state manuals and federal rules, and the CDL practice pack adds full-length sets of 50 + 25 + 20 questions. They are not taken from any state's test and cannot predict your result.
Sources
- 49 CFR 383.135, Passing knowledge and skills tests — eCFR (checked October 3, 2026)
- 49 CFR 383.133, Test methods — eCFR (checked October 3, 2026)
- 49 CFR 383.111, Required knowledge — eCFR (checked October 3, 2026)
- 49 CFR 383.71, Driver application and certification procedures — eCFR (checked October 3, 2026)
- 49 CFR 383.25, Commercial learner's permit — eCFR (checked October 3, 2026)
- CDL knowledge test — Washington State Department of Licensing (checked October 3, 2026)
- CDL Written Knowledge Test — Utah Driver License Division (checked October 3, 2026)
- New York State Commercial Driver's Manual (CDL-10), Section 1 — NYS DMV (checked October 3, 2026)
- California Commercial Driver Handbook — California DMV (checked October 3, 2026)
- Commercial Driver's Licenses (CDL) — California DMV (checked October 3, 2026)
passmock is an independent practice service. It is not affiliated with or endorsed by the Federal Motor Carrier Safety Administration (FMCSA), the U.S. Department of Transportation, the American Association of Motor Vehicle Administrators (AAMVA) or any state DMV, DPS or driver licensing agency. Our questions are original practice questions written from the official state CDL manuals and federal regulations; they are not taken from any state's test.
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