Free practice test
CDL General Knowledge practice test
The free test below follows the real General Knowledge test: 50 questions, 40 right to pass, about 60 minutes. Everyone who applies for a CDL takes it, whatever the class, so it is the first test to practice.
FirstTry CDL is not affiliated with any DMV, FMCSA or government agency. Practice questions are exam-style questions built from the official CDL manual, not actual test questions.
How the General Knowledge test is scored
You need 40 of 50 right, which is 80%. That means you can miss 10. Every CDL applicant takes General Knowledge. It comes first, and it opens the door to every other test.
What is on the General Knowledge test
- Vehicle inspection: what to check and what counts as a defect
- Basic control: steering, backing, shifting and braking
- Seeing and communicating: mirrors, scanning ahead, signals
- Speed and space management: following distance, stopping distance, curves
- Night driving and bad weather: wet roads, ice, fog
- Hazards, skids and emergencies
- Railroad crossings
- Driver fitness: fatigue, alcohol, drugs and phones
- Cargo: weight, balance and tie-downs
- Hazardous materials basics: placards and the rules every driver must know
What trips drivers up
Following distance
Leave at least 1 second for every 10 feet of vehicle length when you drive under 40 mph. Add 1 second above 40 mph. A 60-foot truck at 55 mph needs 7 seconds.
Stopping distance grows fast
Double your speed and your braking distance becomes four times as long.
Hydroplaning starts earlier than you think
On a wet road it can start at speeds as low as 30 mph.
Tire tread
Front tires need at least 4/32 inch of tread. Other tires need at least 2/32 inch.
Railroad crossings
A bus or a placarded vehicle must stop at a crossing. Stop between 15 and 50 feet from the nearest rail.
Cargo checks
Check your cargo and tie-downs within the first 50 miles of a trip. Then check again every 3 hours or 150 miles.
Numbers come from the CDL manual and federal rules. A few differ by state or manual edition, so check your own state's manual. See our sources.
More practice tests
Common questions
How many questions are on the CDL General Knowledge test?
The national default is 50 questions, and you need 40 right (80%) to pass. A few states use a different count, so check your state's manual.
How long do I get for the General Knowledge test?
About 60 minutes in most places. The time limit is set by your state. Our timed practice test uses 60 minutes.
How many questions can I miss and still pass?
On a 50-question test you can miss 10. That margin disappears fast if you guess on a whole topic, so find your weak topics first.
Is the General Knowledge test hard?
It is fair if you study the right parts. Most drivers who fail lose points on a few topics, like space management, skids and inspections. The free Diagnostic shows you yours.
Which other tests do I take with General Knowledge?
It depends on your class and endorsements. Class A usually adds Combination Vehicles and Air Brakes. Class B usually adds Air Brakes. See the class pages for the full list.