CDL General Knowledge Practice Test: Free Sample Questions and Study Guide

The CDL General Knowledge test is the foundation of every commercial driver's license — every Class A, Class B, and most Class C applicants in the United States have to pass it before they can move on to endorsements or the road test. The good news: it's a written exam built on a single federal framework (the FMCSA Model Commercial Driver's License Manual), so once you know the material, the test is the same nationwide.

This guide walks you through exactly what's on the test, gives you free sample questions you can take right now, and lays out a study plan that actually works.

What's on the CDL General Knowledge test?

The General Knowledge test typically has 50 multiple-choice questions and you need a score of around 80% or better to pass (49 of 50 states use the 80% threshold; a few set a slightly different bar). The test is closed-book, no notes, no phones.

The questions are pulled from these federal-CDL topic areas:

• Driving safely — speed management, space management, seeing hazards, communicating, and night/winter driving
• Vehicle inspection — pre-trip, en-route, and post-trip inspection procedures
• Basic control of your vehicle — accelerating, steering, stopping, backing
• Shifting gears — manual transmission patterns and rules even if you'll drive an automatic
• Air brakes basics — even General Knowledge asks about air brakes; the dedicated Air Brakes endorsement goes deeper
• Hazardous driving conditions — rain, ice, fog, mountain driving, work zones
• Accident procedures — what to do at the scene, when to call for help
• Distracted, fatigued, and impaired driving — including the 0.04% BAC limit for CMV drivers (half the limit for non-commercial drivers)
• Hours of Service rules — 11-hour driving limit, 14-hour on-duty window, 30-minute break, 60/70-hour rule
• Cargo basics — securement, weight, balance, hazardous-material awareness
• The CDL Drug & Alcohol Clearinghouse — what it is, when you'll be queried, what disqualifies you

Try free CDL General Knowledge sample questions right now

Stop reading and take our free 10-question CDL General Knowledge quiz on the home page. It takes about 5 minutes, the questions are identical in style to the real test, and you'll see your score with explanations at the end.

Take the free 10-question CDL quiz →

If you score under 70%, that's totally normal for a first attempt — most test-takers do. The point isn't to ace it cold; the point is to find your weak areas so you know where to study.

Five sample CDL General Knowledge questions (with answers)

Try these five before reading the answers. Honest attempt first, then check yourself.

1. The legal blood alcohol limit for commercial drivers operating a CMV is: A) 0.08% B) 0.04% C) 0.10% D) 0.02%

2. The minimum tread depth for steering-axle tires on a commercial vehicle is: A) 2/32 inch B) 3/32 inch C) 4/32 inch D) 6/32 inch

3. You should always do a pre-trip inspection: A) Once a week B) Before driving and after driving C) Only when you suspect a problem D) Once at the start of each shift

4. When driving on a slippery road, you should: A) Slow down gradually and increase following distance B) Brake hard if the truck starts to skid C) Maintain normal speed but keep both hands on the wheel D) Pump the brakes constantly

5. The federal Hours of Service "11-hour rule" means: A) You can drive a maximum of 11 hours after 10 consecutive hours off duty B) You can be on duty a maximum of 11 hours per day C) You can drive 11 hours per week D) You must take an 11-minute break every hour

Answers: 1) B — 0.04%. 2) C — 4/32 inch on steering tires (other tires are 2/32). 3) B — every trip, both before and after. 4) A — slow down gradually and add following distance. 5) A — 11 driving hours after 10 consecutive off-duty hours.

If you missed two or more, that's a clear signal to spend more time in the General Knowledge section before scheduling your test.

High-yield topics that show up on almost every test

After helping thousands of drivers prep for the CDL General Knowledge test, we've noticed a handful of topics show up over and over. Master these and you'll cover the majority of likely questions:

1. The 7-step pre-trip inspection sequence — even General Knowledge will ask 1-3 questions about pre-trip
2. Stopping distance — perception distance + reaction distance + braking distance, and how each one changes with speed
3. Following distance rule — one second per 10 feet of vehicle length under 40 mph; add one second over 40 mph
4. Backing safely — back to the driver's side when possible, get out and look (GOAL), use a helper, no parked-vehicle mirror tricks
5. The 0.04% BAC limit for CMV drivers — and the fact that an out-of-service order applies for 24 hours
6. Hours of Service basics — 11-hour drive, 14-hour window, 30-minute break, 60/70-hour weekly limits
7. Cargo securement — minimum number of tie-downs based on length and weight
8. What disqualifies you — refusing a drug/alcohol test, leaving the scene of an accident, using a CMV in a felony

A 4-week study plan for the General Knowledge test

Week 1 — Read the manual. Get the federal CDL manual (every state DMV website has it free as a PDF) and read the General Knowledge section cover to cover. Don't try to memorize anything yet — just absorb. Take a baseline 10-question quiz at the end of the week.

Week 2 — Drill high-yield topics. Use a question bank to do 30-50 questions per study session, focused on the seven high-yield topics above. Always read the explanation for any question you miss, even if you guessed and got it right.

Week 3 — Mixed practice. Switch to 50-question simulated practice tests covering the full General Knowledge topic mix. Aim to consistently score 80% or better.

Week 4 — Exam mode. Take three full 50-question simulated exams in "exam mode" (no answer reveals until the end) at different times of day. If you're scoring 85% or better, you're ready to schedule the real test.

How many practice questions do I really need to do?

Research on test prep is consistent: students who answer 400+ unique practice questions before sitting for an exam pass at significantly higher rates than those who do 50 or 100. That's why our practice bank has 670 questions spanning General Knowledge, every endorsement, and every CDL section — enough to expose you to virtually every type of question the real test might throw at you.

Unlock the full 670-question bundle for $49.95 →

What's the best free CDL General Knowledge study tool?

If you're not ready to commit to a paid bundle yet, here's the most useful free study sequence we know of:

1. Download the official CDL manual for your state (search "[your state] CDL manual PDF") and read just the General Knowledge section
2. Take our free 10-question CDL practice quiz to baseline your knowledge
3. Install our free CDL Prep Practice Test app for iOS or Android — hundreds of free practice questions you can drill on breaks
4. Watch a YouTube walkthrough of the pre-trip inspection from a CDL school instructor (search "CDL pre-trip inspection walkthrough")
5. Find your state DMV's free practice quiz — most state DMV sites have a small set of sample questions, useful for getting a feel for the question format

This free study sequence will get most experienced drivers across the line. New drivers (especially anyone new to commercial vehicles) typically benefit from the additional depth and structure of a paid study guide — see the 210-page eBook for the structured option.

CDL General Knowledge test FAQ

How long does the CDL General Knowledge test take? Most test-takers finish in 30-45 minutes. Most state DMVs allow up to 90 minutes.

Can I take the General Knowledge test multiple times if I fail? Yes — every state allows retakes, though most require a waiting period (usually 24 hours to 7 days) and may charge a re-test fee.

Is the General Knowledge test the same for Class A, B, and C? The General Knowledge questions are the same federally; what differs is which other tests you have to take alongside it. Class A drivers also take Combination Vehicles. Air Brakes, HazMat, etc. are added based on the endorsements you want.

Do I need to take the General Knowledge test in the same state where I live? Yes — your CDL must be issued by your state of legal residence. If you've moved, you'll typically need to transfer your existing CDL within 30 days.

Where can I download the official CDL manual? Each state DMV publishes its own version, but they're all derived from the FMCSA Model Commercial Driver's License Manual published at fmcsa.dot.gov. You can also find your state's manual by searching "[your state] CDL manual PDF."

What to do next

1. Take the free 10-question CDL practice quiz on our home page right now to baseline your knowledge.
2. Review the high-yield topics above for any you scored poorly on.
3. Get the full 670-question practice bank + 210-page study guide for $49.95 if you want comprehensive coverage and pass-on-first-try preparation.
4. Download our free CDL Prep app for iOS or Android to drill questions on breaks, between deliveries, or anywhere you have 5 minutes.

The General Knowledge test isn't designed to fail people — it's designed to make sure you know the basics of safely operating a commercial vehicle. With the right material and a few weeks of consistent study, passing on the first try is very achievable.

Good luck out there.