Practice tests
CDL practice test: general knowledge and the CLP rules
Practice the general knowledge test that every commercial applicant takes first, then check your commercial learner's permit dates with the CLP tool.
Your score · California
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| Pass mark: 21 of 26 (80 %) |
| You can still miss 5 |
Practice questions written from the state handbook and federal rules. Not the official test.
A commercial driver's license starts with a written general knowledge test and a commercial learner's permit (CLP), under federal rules every state applies. Under 49 CFR 383.25, the CLP is valid for no more than one year, and you must hold it at least 14 days before taking the skills test. While on the permit, you drive only with a CDL holder of the right class physically beside you. Every knowledge test, the general one and each endorsement test, is passed with at least 80 % of correct answers (49 CFR 383.135). To drive a commercial vehicle across state lines you must be 21, under 49 CFR 391.11; within one state, the age set by state law applies, often 18. Since 2022, first-time Class A and B applicants must also finish entry-level driver training from a registered provider before the skills test. Our practice test has 18 questions written from those federal rules, each with its source and an explanation.
Commercial learner's permit (CLP): your dates
Skills test allowed
In 9 days
| CLP expires in | 360 days |
| Interstate driving | Not before 21 |
| Pass mark per test | 80 % |
14-day and one-year limits: 49 CFR 383.25. Age 21 for interstate driving: 49 CFR 391.11.
Questions and state rules by Radif Partners · Editorial policy · How the questions are written
The steps from car license to CDL
The commercial license sits on top of a regular license: you need a valid non-commercial license first. Then come a medical certificate, the knowledge tests, the commercial learner's permit, training, and the skills test. The order below is the one set by the federal rules in 49 CFR part 383; the state agency runs each step and sets the fees.
- Medical certificate. A DOT physical by a certified examiner, valid for up to 24 months, required for most interstate drivers (part 391).
- Knowledge tests. General knowledge, plus air brakes and combination vehicles for Class A, plus any endorsement. Each is passed at 80 %.
- Commercial learner's permit. Issued after the tests, valid up to one year, held at least 14 days before the skills test.
- Entry-level driver training. Required since February 2022 for a first Class A or B, an upgrade from B to A, and a first P, S or H endorsement, from a provider listed in the federal registry (part 380).
- Skills test. Pre-trip inspection, basic control and an on-road drive, in a vehicle of the class you apply for.
License classes and endorsements
The class depends on the vehicle you will drive, not on what you carry. Endorsements are added for specific uses, each with its own knowledge test and, for some, a skills test.
| Class | Vehicles covered |
|---|---|
| A | Combination of vehicles with a gross combination weight rating of 26,001 lb or more, the towed unit over 10,000 lb |
| B | Single vehicle rated 26,001 lb or more, or such a vehicle towing up to 10,000 lb |
| C | Smaller vehicle carrying 16 or more people including the driver, or placarded hazardous materials |
| Code | Endorsement |
|---|---|
| H | Hazardous materials (knowledge test and a federal security check) |
| N | Tank vehicle |
| P | Passenger vehicle (knowledge and skills tests) |
| S | School bus (knowledge and skills tests) |
| T | Double and triple trailers |
| X | Combined tank vehicle and hazardous materials |
Your CLP dates
The CLP tool above counts from the day the permit was issued. The skills test cannot be taken before day 14, and the permit expires after one year at most; some states allow a single renewal, others ask you to retake the knowledge test. Age also matters for where you can drive: under 21, a CLP or CDL is valid only within your state, if state law allows it, because 49 CFR 391.11 sets 21 as the minimum for interstate commerce.
Rules the general knowledge test likes to ask
Hours of service. For property-carrying drivers, part 395 allows 11 hours of driving after 10 consecutive hours off duty, within a 14-hour window, with a 30-minute break after 8 hours of driving, and a weekly cap of 60 hours in 7 days or 70 in 8.
Alcohol and drugs. The commercial limit is 0.04 blood alcohol, and no alcohol at all within four hours of going on duty (part 392). Employers test under part 382, and violations are recorded in the federal Drug and Alcohol Clearinghouse.
Inspection. The driver must be satisfied the vehicle is in safe condition before driving and report defects at the end of the day (part 396). The pre-trip inspection is also the first part of the skills test, so the knowledge questions on brakes, tires, lights and coupling devices pay twice.
Railroad crossings and space. Commercial vehicles that must stop at crossings include buses with passengers and placarded hazmat loads. Following distance is longer than for cars: about one second per ten feet of vehicle length at low speed, plus one second above 40 mph.
The other knowledge tests
General knowledge is only the first written test. A Class A applicant also takes the combination vehicles test, and anyone who will drive a vehicle with air brakes takes the air brakes test; without it, the license carries an air brake restriction. Each endorsement adds its own test, and hazmat adds a federal security threat assessment. All of them use the same 80 % line, so plan the session at the agency to fit several tests in one visit.
How to use the practice test
Run the CDL test until you clear 80 % with room to spare, then read the explanation of each miss: each question names the federal section it comes from. The state commercial driver manual remains the reference for your test, and your state agency for fees and appointments. If you also need a car or motorcycle permit, the written test practice and the motorcycle test work the same way. This page is an independent study aid and is not issued by any licensing agency.