CDL Practice Test 2026: All 9 Exams Explained

A CDL is not one exam. Depending on the vehicle you plan to drive and the loads you plan to carry, you will sit somewhere between two and nine separate tests. Here is what each one covers, who has to take it, and how the written ones are scored.

Nine exams sounds like a mountain. In practice nobody sits all nine. Federal rules give you one test every applicant takes, two more that depend on the vehicle under you, five endorsement tests you only take if you need what they cover, and one that is not a written test at all.

Here is what each one is, and how to work out which of them actually have your name on them.

The one exam every applicant takes

General Knowledge is the base test for every commercial license, whatever the class. Federal rules list the twenty subject areas it draws from (49 CFR 383.111): safe operations regulations, safe vehicle control systems, CMV safety control systems, basic control, shifting, backing, visual search, communication, speed management, space management, night operation, extreme driving conditions, hazard perceptions, emergency maneuvers, skid control and recovery, the relationship of cargo to vehicle control, vehicle inspections, hazardous materials, mountain driving, and fatigue and awareness.

That list is why General Knowledge feels so broad. You will see hazmat awareness questions on it even if you never intend to haul a placarded load, and questions on mountain driving in a state with no mountains.

How many questions you get is set by your state, not by Washington. What is federal is the pass mark: you must answer at least 80 percent correctly (49 CFR 383.135).

The two that depend on the vehicle

Neither of these is an endorsement. They are knowledge you have to prove for the vehicle you intend to drive.

Air Brakes. Required of anyone driving a CMV with air brakes, covering nomenclature, the dangers of contaminated air supply, what a disconnected air line means, low pressure warnings, inspection procedure and general operating practice. Fail this part, or take your skills test in a vehicle without air brakes, and the state puts an L restriction on your license: no air-brake CMV at all. Test in a vehicle with air-over-hydraulic brakes and you get a Z restriction instead, barring full air brake systems (49 CFR 383.95 and 383.153). The full walkthrough is in the air brakes guide.
Combination Vehicles. The Group A test: coupling and uncoupling a tractor to a semi-trailer, combination-specific inspection, and safe operating practice. Group A means any combination rated 26,001 pounds or more GCWR where the towed unit is rated over 10,000 pounds (49 CFR 383.91). If that is your vehicle, this one is not optional — see Class A vs Class B.

The five endorsements

Endorsements are add-ons. You take the ones your work requires, and each carries its own letter on the license (49 CFR 383.93 and 383.153).

T — Doubles and triples. Knowledge test only.
N — Tank vehicle. Knowledge test only. The definition is precise: a tank with an individual rated capacity of more than 119 gallons and an aggregate rated capacity of 1,000 gallons or more (49 CFR 383.5). It is the rated capacity that counts, not how much is in it today.
H — Hazardous materials. A knowledge test at the counter, but the longest route of the five. It also needs a TSA security threat assessment with fingerprints (49 CFR part 1572), and since February 7, 2022 the theory portion of entry-level driver training from a provider on FMCSA's registry. It is the only endorsement whose knowledge test you must pass again at every renewal (49 CFR 383.73).
P — Passenger. Knowledge and a skills test. It covers vehicles designed to carry 16 or more people including the driver.
S — School bus. Knowledge and a skills test, and you must also qualify for the passenger endorsement (49 CFR 383.123).

An X on a license is not a sixth test. It is shorthand for holding N and H together.

The ninth one is not written

Pre-trip inspection is the first of the three parts of the skills test (49 CFR 383.113), alongside basic vehicle control and safe on-road driving. You walk the vehicle with an examiner and say aloud what you are checking and what you are checking it for.

It sits on a study list because it is learned the same way — a fixed body of items recalled in a fixed order — and because it is the part people arrive least prepared for. Reading it silently does not work. You have to speak it. There is a section-by-section breakdown in the pre-trip guide and the wider picture in the three parts of the skills test.

What is federal and what your state decides

The 80 percent pass mark applies to every CDL knowledge test, everywhere (49 CFR 383.135).
The number of questions on each test is a state decision, so the count you read on a forum may not be the count you sit.
Fees, retest waiting periods and how many attempts you get before starting over are also set by the state.
A permit comes first. Passing the knowledge tests gets you a commercial learner's permit, and you cannot take the skills test during the first 14 days after it is issued (49 CFR 383.25).
Age. Interstate driving requires 21 (49 CFR 391.11). Most states will issue an intrastate-only CDL at 18 with a K restriction until your birthday, but that is a state call, not a federal one.

Your state's CDL manual is free and is the document your test is written from. Download it and use it to confirm counts, fees and anything above marked as state-set.

Practicing so the answer sticks

Recognizing a right answer is not the same as knowing why it is right, and the second one is what survives a reworded question. CDL Prep Exam 2026: Permit covers all nine of these subjects as separate practice sets — General Knowledge, Air Brakes, Combination Vehicles, HazMat, Tank Vehicles, Doubles and Triples, Passenger, School Bus and Pre-Trip Inspection — with a clear explanation after every answer, timed mock exams, and a review pass over the questions you missed. You pick your class and endorsements, so you only study what your license actually needs.

What to do next

Start by writing down which of the nine apply to you:

Everyone: General Knowledge.
Air brakes on the vehicle: Air Brakes.
Tractor-trailer or anything Group A: Combination Vehicles.
Pulling two or three trailers: T.
Liquid or gas over the 119 and 1,000 gallon thresholds: N.
Placarded loads: H, plus the TSA check and the training.
Sixteen or more passengers: P.
Students to and from school: S, plus P.
Everyone again: pre-trip, on skills test day.

Most first-time applicants land on three or four, not nine. Download your state's CDL manual to confirm the counts and the fees, then work General Knowledge first and do not add an endorsement until you are clearing it consistently. Twenty questions a day is enough if you read every explanation rather than only the score. Book the permit test once your practice scores hold steady, and spend the 14-day wait before the skills test on pre-trip and on whichever endorsements you listed.