General Knowledge study guide
Required for every CDL applicant. · Exam length: 50 questions · Passing score: 80%.
What this exam covers
The General Knowledge exam is required for every Class A, B, and C CDL applicant. It covers vehicle inspection, basic control, shifting, backing, communicating with other drivers, distracted driving, fatigue, hazard perception, emergency maneuvers, skid control, accident procedures, hazardous materials awareness, and federal hours-of-service rules.
Why this endorsement matters
The General Knowledge knowledge test exists because of a specific real-world hazard. Federal investigators studied decades of crash data and identified a recurring pattern that demanded a written-exam standard for any driver who would face that risk. Passing this exam tells your employer, the FMCSA, and the public that you understand the underlying rules well enough to make safe decisions when nobody is watching.
Common pitfalls
- "Best answer" wording. Several questions on this exam present two answers that are technically true but only one that’s the most complete or most directly responsive. Read every choice before clicking.
- Numerical thresholds. Distances, pressures, weights, and time intervals come up constantly. Memorize the FMCSA numbers exactly, not approximations.
- Procedure order. The test loves to ask you what to do first in a multi-step procedure. Walk through pre-trip, coupling, uncoupling, and emergency-response sequences in order until you can recite them.
Recommended preparation
- Read the General Knowledge section of your state’s CDL handbook end-to-end.
- Take the LicenseReady practice test cold — don’t worry about scoring, just see where you stand.
- Re-read the handbook chapter, paying extra attention to the topics you missed.
- Drill the practice test until you score above 90% on three consecutive attempts.
- Schedule the official exam.
How long should this take?
Most candidates need 4-6 hours of focused study to pass any single CDL endorsement, plus reading time for the handbook. The General Knowledge exam takes longer because it covers everything; specialty endorsements like Tanker and Doubles/Triples are shorter exams with narrower content and can be conquered in a single weekend if you commit. Hazmat is the outlier — the exam is 30 questions, the content is dense, and you also need to apply for the TSA background check, which can take several weeks to clear.
Deep-dive topic articles
Each subtopic below is a stand-alone study article paraphrased directly from the FMCSA CDL Manual section it covers. Work through them in order before you drill the practice test.
- Pre-Trip Inspection — A systematic seven-step pre-trip walk-around to catch defects before they put you and the public at risk.
- Basic Vehicle Control — Backing, turning, and low-speed maneuvering safely with a vehicle whose blind spots are larger than most cars are long.
- Hazard Perception — Reading the road, recognizing developing problems, and acting before they become emergencies.
- Emergency Maneuvers — Braking, steering, and skid control when something goes wrong.
- Hours of Service — The federal limits on driving and on-duty time, and the records that prove you complied.
Ready to practice?
Jump straight into the General Knowledge practice test, or pick your state for a state-framed version of the same exam.