Commercial Driver’s License (CDL) · Knowledge Test Overview
General Knowledge
On this page 6 sections
In 30 seconds
General Knowledge is a 50-question multiple-choice test that covers the whole federal CDL manual at a basic level: vehicle inspection, safe driving, cargo, and the rules that apply to every commercial driver. You need 40 correct answers, which is 80 percent. Every class of CDL, A, B, and C, requires it, and it is the test you must pass before your state will issue a CLP. Pass it, and the rest of your testing path opens up.
Why this matters
The General Knowledge test is the gate every CDL applicant walks through first. You cannot get a Commercial Learner's Permit or schedule a skills test until you have passed its 50 questions with at least 40 correct.
The college version
In normal terms
- Fifty questions, forty right, no exceptions for any class of license.
- It is broad rather than deep, so study the whole manual instead of one favorite chapter.
- Pass it first, because your learner's permit and every other test wait on it.
- You get to miss ten questions, so one hard question is never the end of your day.
Concepts in this outline
- General Knowledge: 50 questions — The largest knowledge test, sampling the whole federal manual with emphasis on inspection, safe driving, cargo, and compliance rules.
- Passing score: 40 (80%) — Forty correct answers out of fifty pass; there is no partial credit and no curve, so 39 is a fail.
- Required for: All CDL classes — Class A, B, and C applicants all take the same General Knowledge test regardless of endorsements.
- CLP: must pass General Knowledge test first — The permit is issued only after this test, and the permit must then be held at least 14 days before the skills test.
Eli explains
The same idea, in plain words
Explain it like I’m 10
Picture a big playground with a fence around it. Most CDL knowledge tests are like tickets for one thing inside: air brakes, combination vehicles, tankers. The General Knowledge test is the ticket for the front gate. It asks a little about almost everything inside. That is why it has more questions than any other knowledge test. The other tests top out at 30 questions or fewer. This one has 50.
The passing score is 40 correct out of 50, which is 80 percent. Remember that number. The same 80 percent bar shows up on nearly every other CDL knowledge test. There is no curve, so your score is not adjusted for other people, and no partial credit. Each question is right or wrong, and 40 right is the line. A driver with 39 correct does not pass and has to come back.
The 50 questions cover the everyday things a professional driver must know cold. Expect vehicle inspection basics, like what to check in the engine compartment and on a walk-around. Expect a lot from the high-priority safe-driving chapter. That means speed and space management, seeing and being seen, night and bad-weather driving, skid control, and stopping distances. Expect cargo questions about spreading weight evenly and tying loads down. Expect rule questions too. One is the 0.04 percent blood alcohol limit for CDL holders. Another is hours of service, the rules on how long you may drive. Hazmat and passenger questions show up only lightly, because those have their own tests.
The gate matters for your Commercial Learner's Permit, or CLP. In every state, the CLP is issued only after you pass General Knowledge. That is why it is the first step in the testing order. Once you hold the CLP, you must keep it at least 14 days before the skills test. So a delay on General Knowledge pushes back every other date. Many drivers take General Knowledge and the Air Brakes test on the same visit to save a trip. But General Knowledge is the one the permit depends on.
How the test is given varies by state. Most states use a computer at the licensing office and show your score right away. Retake waiting periods and fees vary too, and your state's CDL manual lists them. The content does not vary. It comes from the same federal manual everywhere, and the bar is always 80 percent.
You need 40 of the 50 questions, not all of them. Never freeze on one hard question. Answer it as well as you can and move on. Keep collecting the easy ones. Most people who fail miss the basics, not trick questions.
Worked example
Marisol Ortega wants a Class B license to drive a straight truck for a beverage distributor. She reads the manual one chapter at a time and takes a practice test after each chapter, logging every question she misses. In the last week she drills the most-missed topics: hill parking, the 0.04 percent BAC rule, the 100-foot railroad passing rule, sign shapes, and the 290-foot stopping distance at 55 mph.
On test day she brings her medical certificate and non-commercial license, sits at the computer terminal, and works through all 50 questions. She flags two she is unsure of and finishes the rest before going back. Her score comes up as 44 out of 50, comfortably above the 40 she needed. The clerk issues her Commercial Learner's Permit that afternoon, and she marks her calendar 14 days out for the earliest possible skills test.
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