This CDL study guide is for first-time drivers going for a Class A CDL. It covers what’s on the CDL general knowledge test, the steps from permit to license in the right order, a simple 4-week study plan, and the facts that trip people up. You need 80% to pass each knowledge test, and every fact below was checked against the federal rules and current state CDL handbooks.
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CDL study guide: what’s on the general knowledge test
Every CDL applicant takes the general knowledge test. Class A drivers usually take two more knowledge tests before they get a commercial learner’s permit (CLP):
| Knowledge test | Who takes it |
|---|---|
| General Knowledge | Every CDL applicant |
| Combination Vehicles | Class A (tractor-trailer) |
| Air Brakes | Anyone driving a truck with air brakes. Skip it and you get an “L” restriction (no air brakes). |
| Endorsements (H, N, P, S, T) | Only if you want that endorsement |
You need at least 80% on each knowledge test (49 CFR 383.135). Your state decides how many questions there are, so check your DMV’s site for the count.
Most state CDL manuals follow the same national model. The general knowledge test pulls mainly from the early sections: the introduction, Driving Safely, and Transporting Cargo Safely. Check the “which sections to study” chart near the front of your state’s manual, because your state’s manual is what the test is written from.
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CDL study guide: the steps to a Class A CDL, in order
Knowing the order saves you time and money:
- Meet the basics. You have to be at least 21 to drive interstate (many states allow 18 to 20 for in-state only). You also need a valid regular license and a DOT medical card from an examiner on FMCSA’s National Registry.
- Pass the knowledge tests (general knowledge, combination, air brakes).
- Get your CLP. It’s valid for up to 1 year, and you can only drive with a qualified CDL holder in the front seat beside you.
- Complete entry-level driver training (ELDT). It’s required since February 7, 2022 for a first Class A or B CDL. Your school must be listed on FMCSA’s Training Provider Registry, and it reports your completion to the registry.
- Wait at least 14 days after your CLP is issued before the skills test (49 CFR 383.25(e)).
- Take the skills test: pre-trip inspection, then basic vehicle control, then the road test. Fail one part and the test usually ends there. Interpreters aren’t allowed on the skills test.
Our pre-trip inspection checklist walks you through the inspection part step by step.
A 4-week CDL study guide plan
Short daily sessions beat one long cram night.
- Week 1: General knowledge. Read the introduction, Driving Safely and Transporting Cargo sections. Take a general knowledge practice test on day 3 and again on day 6.
- Week 2: Air brakes. Learn how the system works, then the in-cab air brake check. Say the steps out loud.
- Week 3: Combination vehicles. Coupling, uncoupling and trailer skids. Start learning the pre-trip in order.
- Week 4: Review. Retake every practice test. Study only what you missed. You’re ready when you score 90% or better twice in a row on each test.
Want practice tests on paper? The HaulLedger CDL Study Guide & Practice Tests has 75 original practice questions for General Knowledge, Air Brakes and Combination Vehicles, an answer key that explains every answer, and a study tracker. It’s not the real test, but it shows you where your gaps are.
CDL study guide: general knowledge test facts to know cold
These come up in every state manual and trip up a lot of first-timers:
- Following distance: at least 1 second for every 10 feet of vehicle length under 40 mph, plus 1 more second over 40 mph. A 40-foot rig at highway speed needs 5 seconds.
- Look ahead: 12 to 15 seconds down the road.
- Cargo checks: check cargo and securement within the first 50 miles, then at every change of duty status, or every 3 hours or 150 miles, whichever comes first (49 CFR 392.9).
- Tiedowns: an article over 10 feet long needs at least 2 tiedowns, plus 1 more for every extra 10 feet (49 CFR 393.110).
- Warning triangles: put them out within 10 minutes of stopping. On a two-way road, one goes 10 feet from the truck on the traffic side and the others go about 100 feet ahead and behind (49 CFR 392.22).
- Alcohol: 0.04 blood alcohol concentration is the limit for a CDL driver on duty in a commercial vehicle. That’s half the 0.08 limit most states use for car drivers.
CDL study guide tips for test day
- Bring your license, your medical card, and any documents your state lists. Check the DMV site the week before.
- Read every answer choice before you pick one. Look out for “except” and “not” in the question.
- Don’t bring notes or a phone into the test room. Most states fail you for using any testing aid.
- If a question stumps you, mark it and come back if your state’s test allows that.
Once you’re licensed and thinking about running your own truck, our trucking business plan guide shows what it takes to start.
Free: Know Your Number cost-per-mile calculator. See your break-even rate before you book a load.
CDL study guide FAQ
What score do you need to pass the CDL general knowledge test? At least 80% on each knowledge test. That’s a federal minimum in 49 CFR 383.135.
How many questions are on the CDL general knowledge test? It depends on your state. Federal rules set the pass mark, not the number of questions, so check your state DMV’s CDL page.
How long should I study for the CDL permit test? Many people need 2 to 4 weeks of steady study. Use practice tests to decide. When you score 90% or better twice in a row, you’re probably ready.
Is the CDL general knowledge test hard? It’s very doable if you read your state manual and practice. Most people who fail rush it or skip the Driving Safely and cargo sections.
Do I need ELDT before the CDL permit test? No. ELDT comes after you get your CLP and before your Class A or B skills test. Hazmat is different: you need hazmat ELDT before the hazmat knowledge test (49 CFR 383.71).
How long is a CLP good for? Up to 1 year under federal rules. You must hold it at least 14 days before you take the skills test.
Can I study for my CDL on my own? You can study for the knowledge tests on your own with your state manual and practice tests. For a first Class A or B license, you still have to complete ELDT with a registered provider before the skills test.
Use this CDL study guide to pass the first time
Read your state manual, practice until you score 90% or better, and learn the steps in order. If you like studying on paper, the CDL Study Guide & Practice Tests gives you 3 printable practice tests with explained answers, a pre-trip checklist, air brake steps and a test-day checklist.
Educational study aid, not legal advice. Your state’s CDL manual and DMV rules come first, and test formats vary by state. HaulLedger Studio isn’t affiliated with FMCSA, the U.S. DOT or any state. The practice questions are original and are not the questions on your state’s test.
Sources (checked October 2026)
- eCFR, 49 CFR 383.25 (CLP, 14 days, 1 year), 383.71 (ELDT before skills test), 383.135 (80% pass mark), 383.95 (restrictions), 391.11 (age 21), 392.9, 392.22, 393.110, 382.201
- FMCSA, Entry-Level Driver Training and the Training Provider Registry
- California DMV, California Commercial Driver Handbook; Texas DPS, Texas Commercial Motor Vehicle Drivers Handbook