Trucking Careers · Nationwide · October 23, 2026

CDL General Knowledge Test Study Guide: Topics, Scores and Tips

The general knowledge test is the first big exam on the road to a commercial driver's license. Passing it, along with any other required knowledge tests, is what allows a state to issue a commercial learner's permit (CLP). This guide explains the federal rules behind the test, its topics, state differences and official study materials. It does not include practice questions. This is general information, not legal advice.

Where the knowledge test fits in the CDL process

Federal rules in 49 CFR 383.25 say a CLP holder must have passed a general knowledge test that meets federal standards for the type of truck or bus the person plans to drive. After that, the CLP must be held for at least 14 days before the skills test, and most first-time Class A and Class B applicants must also finish entry-level driver training first. The full sequence is laid out in the guide on how to get a CDL step by step.

How the test is built

The federal passing standard

Under 49 CFR 383.135, an applicant must correctly answer at least 80 percent of the questions on each knowledge test to pass. The same section says a driver who fails the air brake portion gets an air brake restriction on the CLP or CDL, and a driver who fails the combination vehicle portion cannot get a Group A CLP or CDL.

Question pools and test versions

According to 49 CFR 383.133, states must use a pool of test questions pre-approved by FMCSA that is comparable to the 2005 CDL Test System developed by the American Association of Motor Vehicle Administrators. The rule also says:

• Each test version must have a set number of questions from each knowledge area.
• Twenty-five percent of the questions must be new compared with the previous version of the test.
• A question repeated from an earlier version must appear in a different location on the test, with its three answer choices in a different order.
• An applicant who retakes a test must get a different version.
• Tests can be written, oral or automated, and a state may offer the test in a foreign language, but not through an interpreter.

Because of these rules, memorizing questions is not a reliable plan. Learning the material in the state CDL manual works better.

What the general knowledge test covers

Federal rule 49 CFR 383.111 lists 20 knowledge areas every CDL applicant must know. They can be grouped into a few themes.

Rules and inspections

• Safe operations regulations, such as inspection and maintenance rules, safe operating procedures, and the effects of fatigue, health, alcohol and drugs on safe driving
• Vehicle inspections, including pre-trip, en route and post-trip procedures and the safety parts to check, such as tires, brakes, steering and coupling systems
• Hazardous materials basics, such as what counts as hazardous material needing an endorsement, hazard classes and labeling and placarding

Drug and alcohol rules stay in the news after the test, too, as in the petition asking FMCSA to stop random drug test notices on days off. Inspection knowledge also matters on the job, as a recent roadside inspection operation in El Paso showed.

Vehicle systems and control

• Safe vehicle control systems and CMV safety control systems, such as lights, horns, mirrors and fire extinguishers
• Basic control, shifting and backing
• Relationship of cargo to vehicle control, including weight distribution and cargo securement

Safe driving skills

• Visual search, communication, speed management and space management
• Night operation and extreme driving conditions, including bad weather and hot weather
• Hazard perception, emergency maneuvers and skid control and recovery
• Mountain driving practices, such as choosing a safe speed and gear and braking on downgrades
• Fatigue and awareness

Hours of service rules fall under safe operations, so the guide to hours of service and ELD rules is useful background, and the hours of service break calculator shows how the driving and break limits work in practice.

Other knowledge tests

The general test is only one piece. Under 49 CFR 383.111 and 383.93, drivers may also need:

• Air brakes, covering seven areas such as air brake parts, low air pressure, inspections and operating practices
• Combination vehicles, covering coupling and uncoupling, inspection and operating practices, for Class A
• Endorsement tests for doubles and triples, tank vehicles, hazardous materials, passenger vehicles and school buses

FMCSA rules allow only passenger, school bus and tank vehicle endorsements on a CLP. Several states, including New Jersey and Virginia, say applicants for the hazardous materials endorsement must complete entry-level driver training before taking that knowledge test.

How states run the test

The examples below come from state licensing agency websites.

Number of questions

• Washington: The Department of Licensing lists 50 questions on the general knowledge test, with 40 correct needed to pass. It lists 25 questions for air brakes and 20 for combination vehicles.
• Iowa: Iowa DOT lists 50 questions on the general test and says applicants can miss 10.
• Utah: The Driver License Division lists a 50-question general test that is closed book and multiple choice, with 80 percent needed to pass.
• New Jersey: The Motor Vehicle Commission describes a 50-question general test, plus separate tests for each endorsement, with 80 percent needed to pass.

The 80 percent standard is federal, but question counts, fees, languages, retest waits and how long scores stay valid are set by each state and can change.

Language, fees and retests

State details vary widely. Washington lists the test in English, Spanish, Russian and Serbian-Croatian and says scores are valid for 180 days. Utah says its written tests are offered in English only, and its core tests are included in the $52 license application fee, with up to two attempts per test before a $26 retest fee. New Jersey lists a $125 test fee and a seven-day wait after a failed knowledge test. Virginia says its exams are taken on a computer, can be taken once per business day, and that the hazardous materials test is given only in English.

How to study using official materials

Start with the state CDL manual

Virginia says its knowledge exam questions come from the Virginia Commercial Driver's Manual, and Utah says its questions are based on its CDL handbook. Virginia's site lists which manual sections to study for each license class and endorsement, such as Driving Safely and Transporting Cargo Safely for all classes. Washington's guide includes a table showing which sections to study.

Use the state's own practice tools

Washington offers a practice test, and Iowa points applicants to a free Iowa CDL practice test app along with its manual.

Study only for the tests needed

Picking the license class and endorsements first keeps study time focused, since passenger or school bus sections apply only to those endorsements.

Follow the testing rules

Virginia's site says it is unlawful to try to get or share copies of exam questions or answers, or to get help during the exam, and that using a cell phone ends the exam.

Frequently Asked Questions

What score is needed to pass the CDL general knowledge test?

Federal rule 49 CFR 383.135 requires at least 80 percent correct on each knowledge test.

How many questions are on the general knowledge test?

It varies by state. Washington, Iowa, Utah and New Jersey each list 50 questions, but check the state licensing agency for current details.

What topics does the general knowledge test cover?

Federal rules list 20 areas, including safety regulations, vehicle inspections, basic control, space and speed management, hazard perception, extreme driving conditions and fatigue.

Can the test be taken in another language?

Federal rules allow states to offer the test in a foreign language, but not through an interpreter. Each state chooses which languages to offer.

What happens after passing?

After passing the required knowledge tests, the state can issue a CLP. The CLP must be held at least 14 days before the skills test, which covers a pre-trip inspection, basic vehicle control and an on-road drive.

This guide is general information, not legal advice. Testing rules, fees and question counts vary by state, so always check the current requirements with the state licensing agency.

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