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CDL General Knowledge Test: What to Study from the Model Handbook

November 5, 2026 · 7 min read

If you are aiming for a commercial learner's permit (CLP) or a commercial driver's license (CDL), the general knowledge test is the one almost everyone takes first. Prep sites often answer "how many questions?" with one confident national number. The Federal Motor Carrier Safety Administration (FMCSA) and the states do not work that way.

This guide sticks to what FMCSA and state licensing agencies publish: the federal pass score, the federal floor on test length, the model handbook study map most states use, and a few states that publish exact counts. Where officials do not publish a single national total, we say so.

Short answers

From FMCSA and 49 CFR Part 383:

  • You must pass a general knowledge test before a State can issue a CLP for the vehicle group you want to operate (49 CFR 383.71(a)(2) and 383.25(a)(3)).
  • To pass each knowledge test, you must correctly answer at least 80 percent of the questions (49 CFR 383.135(a)(1); also stated on FMCSA's States page).
  • FMCSA's States page says each basic knowledge test covers the 20 general areas in 49 CFR 383.111(a) and "shall contain at least 30 items."
  • There is no single national question count published as "the" general knowledge test length for every State. States build their own tests from an FMCSA-approved question pool. Several States that do publish counts use 50 questions with 40 correct to pass (examples below).
  • FMCSA says plainly: use your State's CDL manual. Each State has its own.

So the useful study question is not "what is the national total?" It is "what does my State manual mark for general knowledge, and what else do I need for my class and endorsements?"

Why the question count varies by state

FMCSA does not issue CDLs. States do. FMCSA's States page says States develop their own knowledge and skills tests under Subparts G and H of 49 CFR Part 383, and that model manuals and tests are available for States to use.

Under 49 CFR 383.133, States must use an FMCSA pre-approved question pool and test-generation method. The federal pass rule in 383.135 is 80 percent. The States page adds the "at least 30 items" floor and the link to the 20 knowledge areas. Beyond that floor, States set their own totals.

Third-party sites that invent one national "50 questions everywhere" number are oversimplifying. Fifty is common where States publish a number. FMCSA does not print it as a nationwide fixed length.

States that do publish a general knowledge count

These are live State pages or manuals checked for this article. They are examples, not a 50-State survey:

  • Washington DOL: General knowledge (Classes A, B, and C) is 50 questions, passing score 40. Same table: combination 20/16, air brakes 25/20, hazmat 30/24.
  • Iowa DOT: General knowledge 50 questions / 10 allowed misses. Combination 20/4, air brake 25/5, hazmat 30/6.
  • Idaho CDL Manual (July 2026): General Knowledge 50 questions, 40 minimum correct. Hazmat 30/24, Air Brake 25/20, Combination Vehicles 20/16.

If your State is not listed, do not guess from a practice-test site. Open your State's current CDL manual or knowledge-test page. If it does not publish a count, study to the 80 percent standard and the full general-knowledge sections.

What the model handbook says to study

Federal rules require each State to give applicants an FMCSA-approved driver information manual comparable to AAMVA's model Commercial Driver Manual (49 CFR 383.131). Most State CDL handbooks still use that model structure and a "What Sections Should You Study?" chart near the front.

Texas is a clear example. The Texas Commercial Motor Vehicle Drivers Handbook (DL-7C, revised March 2026) is the State's current manual. It says:

  • Knowledge exams are multiple choice and matching.
  • A score of 80% or higher is required to pass each section.
  • Tests are administered in a fixed order, starting with Texas Commercial Rules, then General Knowledge, then Combination (if required), Airbrakes (if required), and endorsements as needed.
  • Figure 1.2 ("What Sections Should You Study?") marks, for Class A, B, and C licenses, study of Sections 1, 2, and 3 of the model content (Introduction, Driving Safely, Transporting Cargo Safely), plus Section 5 if you will operate vehicles with air brakes, and Sections 11 to 13 when you are preparing for the skills test.

That chart is the model-handbook approach: match sections to the tests you will actually take.

For general knowledge, treat Driving Safely and Transporting Cargo Safely as the core, then add your State's commercial-rules chapter if it has one (Texas Section 14 is one example). Air brakes, combination vehicles, passenger, school bus, tank, doubles/triples, and hazmat are usually separate knowledge tests.

The 20 federal knowledge areas (the real "what's on it")

Whatever your State's question count, the basic knowledge test must cover the 20 general areas in 49 CFR 383.111(a). Grouped for study, those are: safe-operations rules (including fatigue, health, alcohol and drugs); vehicle controls and safety systems; basic control, shifting, and backing; visual search and communication; speed and space management; night and extreme conditions; hazard perception, emergencies, and skids; cargo weight and securement; vehicle inspections; hazardous-materials awareness (what needs an endorsement); mountain driving; and staying alert.

If a practice set never touches cargo securement, space management, or inspection procedures, it is not covering the federal map even if it feels long.

How the general knowledge test fits the rest of the path

Passing general knowledge is necessary, not sufficient.

  • CLP first. Under 49 CFR 383.25, you generally need a CLP before an initial CDL (or before an upgrade that needs a skills test). You are not eligible to take the CDL skills test in the first 14 days after the CLP is issued.
  • Other knowledge tests. Class A usually also needs combination vehicles. Vehicles with air brakes need the air brake knowledge test (or you take an air-brake restriction). Endorsements (passenger, school bus, tank, doubles/triples, hazmat) have their own tests. Hazmat also requires a TSA security threat assessment.
  • ELDT. For many first-time Class A or B applicants, and for first-time passenger, school bus, or hazmat endorsements, federal Entry-Level Driver Training with a provider on the Training Provider Registry applies before skills testing (or before the hazmat knowledge test). Check 49 CFR 383.71 and your State page for the exact trigger that applies to you.
  • Skills test. After the waiting period and any required training, you still take vehicle inspection, basic control, and on-road skills in a representative vehicle.

State details differ. California's CDL page publishes three knowledge-test attempts, no knowledge tests within 30 minutes of closing, and a California-specific 15-hour behind-the-wheel certification for original Class A or B, but it does not state a general knowledge question total. Texas DPS publishes the test order, and the handbook states 80 percent, but the current DPS apply page does not print a general knowledge count.

A practical study plan

  1. Download your State's current CDL manual from the State licensing site (FMCSA's CDL Manual page exists mainly to send you there).
  2. Find the "What Sections Should You Study?" chart (or your State's equivalent) and highlight every section marked for general knowledge for your class.
  3. Read those sections slowly. The model manuals put review questions at the ends of many chapters; use them.
  4. Add State-only chapters (commercial rules, local size/weight rules) if your State tests them separately or first.
  5. Only after the official manual, use practice questions to find weak spots. Practice is a check, not a substitute for the handbook.

Practice after the official manual

Once you have worked through your State handbook, Capxule's CDL general knowledge practice test is a guided set of original questions written from a State CDL handbook based on the national model manual (Texas DL-7C, revised March 2026), in English and Spanish. It is not affiliated with any State DMV or AAMVA, and it is not a dump of official exam items. Use it beside the official manual for your State, not instead of it.

Sources

All checked on November 5, 2026 (America/Los_Angeles):

Rules change. Check your State licensing site and the current CFR before test day.

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