CDL Practice Test
A free 30-question CDL general knowledge practice test: vehicle inspection, air brakes, cargo securement, and safe driving, with explanations for every answer.
Thirty general-knowledge questions of the kind found in every state CDL manual: pre-trip inspection, air brake systems, stopping distance and following distance, cargo inspection and securement, federal weight limits, hours of service, and skid and emergency control. Explanations cite the standard CDL-manual rule behind each answer. Practice only — the real state CDL exam controls.
Practice test only — this is not an official CDL exam. Questions reflect the general-knowledge material in state CDL manuals and long-standing federal standards. Your state's official CDL manual is the final authority for its knowledge test.
30 general-knowledge questions: vehicle inspection, air brakes, cargo securement, speed and space management, and safe driving practices. Practice benchmark: 80% (24 of 30).
How to use this calculator
- Press 'Start the 30-question test' — all 30 general-knowledge questions appear in a shuffled order.
- Answer each question; feedback and a CDL-manual explanation appear immediately.
- Press 'See my score' after the last question.
- Score at least 24 of 30 (80%) to meet the practice benchmark, the level states commonly require.
- Study the review list — inspection, air brake, and cargo questions mirror the core of the real exam.
The formula
Practice benchmark = 80% (24 of 30 correct), the passing level commonly used for state CDL knowledge tests.
Worked example
Example question from the test: the low air pressure warning on an air-brake vehicle must come on before pressure falls below about 60 psi — a standard figure from CDL manuals. Worked scoring check: 27 correct of 30 = 90%, above the 80% benchmark.
Frequently Asked Questions
Is this the official CDL test?
No. It is a practice test covering the general-knowledge material that appears in state CDL manuals. To earn a commercial driver's license you must pass your state's official knowledge and skills tests, and this site is not affiliated with any state or with the FMCSA.
What topics does the CDL general knowledge test cover?
The real general knowledge section covers vehicle inspection, basic control, shifting, seeing and communicating, speed and space management, night and mountain driving, skids, emergencies, transporting cargo, and air brakes for combination vehicles. This practice test samples all of those areas.
Where do the numbers in these questions come from?
From the standard figures taught in CDL manuals and federal rules that apply nationally — for example the low-air warning at about 60 psi, the 20,000 lb single-axle / 34,000 lb tandem / 80,000 lb gross Interstate limits, the 0.04% alcohol limit for CDL holders in a commercial vehicle, and the 11-hour driving limit inside a 14-hour window after 10 hours off.
What score do I need on the real CDL test?
States commonly require 80% on the knowledge test, and this practice test uses 80% (24 of 30) as its benchmark. Your state's exact requirement is in its CDL manual — always treat the manual as the final authority.
Does passing this practice test mean I am ready for endorsements too?
No. This test covers general knowledge only. Tanker, hazardous materials, passenger, school bus, and doubles/triples each have their own additional knowledge tests and rules that this practice test does not cover.