How Many Questions Is the CDL General Knowledge Test? Why It Depends on Your State

Written & reviewed by the Quibank editorial team · Last reviewed 2026-09-06 · Editorial standards

There is no national number. Federal law tells your state where to get the questions and what score you need, but it never says how many questions to put on the test — so the only count you can trust is the one printed in your own state's CDL manual.

That is a genuinely unsatisfying answer to a simple question, and it's also why so many articles confidently give you a figure that turns out not to match the screen in front of you at the DMV. What's worth knowing instead is the part that is identical in all 50 states, because that's the part you can actually prepare against.

What federal law does fix

Three things, and they matter more than the count.

First, the bar: 49 CFR 383.135 requires you to correctly answer at least 80 percent of the questions on each knowledge test. Not 70, not a curve — 80 percent, everywhere. Second, the source: states cannot write their own questions freely. Section 383.133 requires them to draw from an FMCSA pre-approved pool comparable to AAMVA's CDL Test System, and requires each test to contain a set number of questions with a prescribed number from each knowledge area. That is why a Georgia general knowledge test and an Oregon one feel like the same exam even when the totals differ.

Third, and this is the one people learn the expensive way: the same regulation requires a state to use a different version of the test when you retake one you failed. It also requires that 25 percent of the questions on any version be new relative to the previous version, and that repeated questions appear in a different position with their answer choices reordered. Memorizing the specific items you missed is therefore close to worthless. You will not see that test again.

"The written test" is actually several separate tests

This is the single biggest source of confusion among people going for their first commercial learner's permit, and it explains a whole genre of forum thread. General knowledge is one test. Air brakes is another. Combination vehicles is another. Endorsements — hazmat, tanker, passenger, school bus, doubles/triples — are each their own test on top of those.

The consequences are written into federal law rather than left to the clerk. Under 383.135, if you score below 80 percent on the air brake portion you can still be issued a permit or license, but it carries an air brake restriction. Score below 80 percent on the combination portion and you cannot be issued a Group A permit or license at all.

Candidates on TruckersReport's forums run into both outcomes constantly — threads asking why a permit came back with an air brake restriction, and others asking why a permit shows no endorsements after the applicant sat several tests in one visit. Forum members' consistent answer to newcomers is the practical one: a failure is scoped to the test you failed, so you retake that section rather than starting over. Confirm it with your own licensing agency, since scheduling and fees for retakes are a state matter.

What's actually on the general knowledge test

Section 383.111 lists 20 areas of required knowledge that every CMV operator must be tested on. It reads less like trivia and more like a job description:

Safe operations regulations — the driver-facing parts of FMCSA Parts 391, 392, 393, 395, 396 and 397, including inspection and maintenance duties and the effects of fatigue, vision and hearing problems, alcohol and drugs
Safe vehicle control systems, CMV safety control systems, and diagnosing malfunctions — including emergency handling of skids and brake loss
Basic control, shifting, backing, visual search, communication, speed management, space management
Night operation, extreme driving conditions, hazard perception, emergency maneuvers, skid control and recovery
Vehicle inspections, hazardous materials awareness, air brakes, and the requirements tied to the specific vehicle group you're testing for

Two of those deserve extra time. Air brakes shows up both as its own test and inside general knowledge, so the material pays double. And the regulations block — hours of service, inspection duties, disqualifying offenses — is where candidates who learned to drive by driving tend to lose points, because none of it is intuitive from experience behind the wheel.

The 80% math is tighter than it sounds

Run the arithmetic for whatever count your state uses. At 80 percent, a 50-question test allows 10 wrong answers; a 40-question test allows 8. That is a narrow margin on material full of specific numbers, and it's why failing by a single question is such a common story — TruckersReport has threads from candidates who cleared air brakes and combination on the same visit and missed general knowledge by one.

The forum's standard advice to people in that position is worth repeating because it's unglamorous and correct: read your state's actual CDL manual cover to cover rather than relying on practice questions alone, and drill practice tests until you're scoring at or near 100 percent, not merely clearing 80. Candidates there describe practice questions as close to the real wording but not identical — useful for exposing you to how questions are phrased, unreliable as a substitute for the manual. Given that a retake is a different version by law, a margin above the bar is the only thing that actually transfers.

What the knowledge test does not require: ELDT

Since February 7, 2022, entry-level driver training from a provider on FMCSA's Training Provider Registry has been mandatory for anyone getting a Class A or Class B CDL for the first time, upgrading Class B to Class A, or adding a passenger, school bus or hazmat endorsement for the first time.

It does not gate the test most people are asking about. FMCSA's own applicability fact sheet puts the deadline at the skills test — training must be completed before you take the CDL skills test, or, if you're applying for the hazmat endorsement, before that endorsement's knowledge test. The general knowledge test that gets you a commercial learner's permit is not on that list. You can study the manual, pass the knowledge test, and hold a CLP before you have booked a single hour of training.

Two more permit rules catch people out. You are not eligible to take the CDL skills test in the first 14 days after your CLP is initially issued, so the calendar starts the day the permit prints. And a CLP is valid for no more than one year from issuance without retaking the knowledge tests — meaning if training and scheduling drag past that, you pay for and sit the written tests again.

How to prepare

Start with your state's CDL manual, because it is the only document that answers the question you came here with. It states your state's question count and passing requirements, and it is the source the pre-approved question pool is written against.

Then drill by section rather than in one undifferentiated pile, since that's how you'll actually be tested and how a failure will be scoped. When a question turns on a number — following distance, hours of service, inspection intervals, brake adjustment limits — treat it as a memorization item rather than something you can reason to; those are the questions that decide an 80 percent.

Quibank's free CDL practice test is split the way the real testing is: general knowledge, air brakes, and combination vehicles, plus hazmat, tanker, passenger and school bus, and doubles/triples, scored against the federal 80 percent bar, in English, Spanish, and Chinese.

Try the free CDL practice test →