CDL study guide: what to study and how
The best CDL study guide is your state’s CDL manual, which FMCSA tells every applicant to get first and which states offer at licensing offices or as a download. Every state builds its knowledge tests from an FMCSA-approved question pool. Study the general knowledge section first, then the sections for your class and endorsements, and practise until you reach well above the 80 percent you need on each test.
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The official CDL study guide is your state manual
FMCSA tells applicants to start by getting their state’s CDL manual, at a licensing office or as a download. That manual is the official CDL study guide from your state, the same agency that gives the test. States develop their knowledge tests from FMCSA’s pre-approved question pool.
If you want a study guide for CDL tests in print, the state manual is also the one CDL study book every applicant should own. Other CDL books can help with practice, but start with the official material.
Source: FMCSA — How do I get a Commercial Driver’s License?. Checked 19 October 2026.
What a CDL manual covers
California’s commercial handbook is a typical example of how CDL books from state agencies are organised. The first sections cover what every driver needs; later sections cover specific vehicles and endorsements; the last three explain the skills test.
- Driving safely and transporting cargo safely
- Transporting passengers safely
- Air brakes
- Combination vehicles; doubles and triples
- Tank vehicles; hazardous materials; school buses
- Vehicle inspection test, basic control skills test and road test
Source: California DMV — California Commercial Driver Handbook (state example). Checked 19 October 2026.
Which sections to study for your CDL license
When you study for CDL license tests, match the manual to your tests. California’s handbook includes a table showing what sections to study, and names three core tests: the general knowledge test, required of all applicants; the air brakes test, for drivers of vehicles with air brakes, including air over hydraulic brakes; and the combination vehicles test, for anyone who wants to drive combinations. Endorsements add their own sections.
Source: California DMV — California Commercial Driver Handbook (state example). Checked 19 October 2026.
How the knowledge tests are built, and what that means for CDL study
Each state test has a set number of questions with a prescribed number from each knowledge area, and a quarter of the questions on a test must be new compared with the previous version. If you fail and retake a test, you get a different version.
For your CDL study, that means memorising answer lists does not work. Studying for the CDL test should aim at understanding each area well enough to answer a question you have not seen before, and at reaching at least 80 percent in every area, not only overall.
Source: eCFR — 49 CFR 383.133 Test methods. Checked 19 October 2026.
A study plan for the CDL permit test
This is our suggested order, not an official schedule. When studying for CDL exam day, read one manual section at a time and answer questions on it the same day; mistakes show you what to reread.
- Week 1: general knowledge sections (driving safely, cargo) with daily questions
- Week 2: air brakes and, for Class A, combination vehicles
- Week 3: your endorsements, such as tanks, doubles and triples, passengers or hazmat
- Final days: mixed timed sets across all your tests, then reread weak sections
Free sample tests and how to study for the CDL test online
Some states offer free official practice. California DMV publishes two commercial sample tests for Class A or B applicants next to its handbook and adds new questions from time to time. Check your state agency for similar material.
To study for the CDL test online beyond that, use question sets organised by area. Certsqill’s CDL question bank has expert-developed questions, an explanation for every answer option and a readiness score per area, so you can see which manual section to revisit.
Source: California DMV — Sample Driver’s License Knowledge Tests (state example). Checked 19 October 2026.
CDL study guide: questions people ask
What is the best CDL study guide?
Your state’s CDL manual. FMCSA tells applicants to get it first; the state that publishes it also gives the test. Source: FMCSA, checked 19 October 2026.
Is the CDL manual free?
FMCSA says you can pick up your state’s manual at a licensing office or download it. California, for example, publishes its commercial handbook as a PDF. Checked 19 October 2026.
Which CDL books should I buy?
Start with the state manual. Any other CDL books are supplements to the official manual.
How long should I study for the CDL permit test?
No official figure exists. Plan by your tests: general knowledge for everyone, plus air brakes, combination vehicles and endorsements as needed.
What score should I aim for when studying?
You need at least 80 percent on each knowledge test, so aim clearly above that in every area. Source: 49 CFR 383.135, checked 19 October 2026.
