CDL Commercial Drivers License General Knowledge — Everything You Need to Know in 2026

The CDL General Knowledge exam is the first of multiple written tests required to earn a commercial driver's license. It covers general truck-driving knowledge: vehicle inspection, basic controls, shifting, backing, coupling, cargo handling, hazardous materials basics, and federal driving regulations.

This is a written knowledge test, not a driving test. Most states administer it at the DMV or a state-authorized testing site. You need 80% to pass — 40 out of 50 questions correct. The content is federally standardized, so the material is the same across all 50 states even though the test fee and scheduling process differ.

Passing the General Knowledge exam earns you a Commercial Learner's Permit (CLP). From there you can take endorsement tests (Hazmat, Passenger, Tanker, Doubles/Triples, Air Brakes) and eventually the behind-the-wheel skills test for the full CDL. Class A allows tractor-trailers, Class B covers straight trucks and buses, and Class C covers smaller commercial vehicles.

You need 80% to pass — that's at least 40 correct out of 50 scored questions.

Schedule through your state DMV or an authorized CDL testing site. Some states accept walk-ins; most require an appointment. The fee varies significantly by state — from under $20 in some states to over $100 in others.

You need a valid non-commercial driver's license to apply. In most states, the process is: pass the knowledge test → receive your CLP → practice driving with a qualified CDL holder for the required holding period (usually 14 to 60 days) → pass the skills test.

There are no formal education prerequisites. You must be at least 18 to drive intrastate (within your state) and 21 to drive interstate (crossing state lines). A valid non-CDL driver's license is required.

For certain endorsements, additional requirements apply. Hazmat certification requires a TSA background check and fingerprinting. Passenger and School Bus endorsements require a clean motor vehicle record. Individual employers may have their own age, MVR, and physical requirements on top of the federal minimums.

First-year company truck drivers typically earn $45,000 to $65,000 in base pay, with regional and OTR (over-the-road) long-haul drivers on the higher end. Owner-operators can earn more — or less — depending on fuel costs, loads, and their operating authority.

Many carriers offer signing bonuses of $5,000 to $15,000 for new CDL holders who commit to a term contract. Major companies like Schneider, Werner, Swift, and Prime actively recruit new CDL graduates and often provide paid training in exchange for a 1-year commitment.

Most candidates need 2-4 weeks to be ready. The candidates who fail typically do one of three things: they cram at the last minute, they study everything equally instead of targeting their weak areas, or they read passively without testing themselves. All three are fixable.

The most effective approach: take a practice test first, before you've studied anything. Your score tells you exactly which of the 4 topics need the most attention. Then focus your flashcard sessions on those weak areas using spaced repetition — reviewing at increasing intervals so the information actually sticks.

As your exam date gets closer, switch to full timed practice tests under realistic conditions. You want to be scoring comfortably above the passing threshold before you walk in.

CDL drivers earn $50,000-$80,000+ per year. Regional and OTR (over-the-road) routes pay more. Owner-operators can earn significantly more. The trucking industry consistently has more demand than qualified drivers.

Once you know your weak areas, flashcards are the fastest way to close the gaps. Prepdex builds your study sessions around the topics where you're losing points — not a generic review of everything.

Each session takes about 10-15 minutes. You study the topics that matter most for your score, in the order the exam weights them. The spaced repetition scheduling makes sure you see things again before you forget them.