CDL Prep HeroThe pass mark is 80 percent
49 CFR 383.135 says an applicant must correctly answer at least 80 percent of the questions on each knowledge test. That is a separate score for each test, not one combined score for the whole visit. The same section ties two failures to the credential itself. Fail air brakes, and an issued permit or license carries an air-brake restriction. Fail the combination-vehicle portion, and the state must not issue a Group A permit or license.
A practice score of 80 percent on this website is a label on our questions. It is not the official result. How to read a practice score keeps those two numbers apart.
Which tests you take for Class A, Class B, and endorsements
The class decides the vehicle-group tests. Class A is the combination group, so the combination test is the one that can block the license. Class B is the heavy straight vehicle and does not require that combination test. Air brakes are required only in the sense that skipping them, or failing them, leaves the restriction. Illinois says you take the air-brake knowledge test if the vehicle is so equipped.
Endorsements add tests on top. Double and triple trailers, tank, and hazardous materials are knowledge tests. Passenger and school bus are knowledge and skills tests. A learner's permit can show only passenger, school bus, and tank. Hazmat is not placed on the permit.
Texas inserts a state test at the front. The order is Texas Commercial Rules, General Knowledge, Combination for Class A only, Air Brake if it applies, then endorsements, and as of June 1, 2026 those knowledge exams are in English only. New York offers Class A, B, and C written tests and endorsements in English, Spanish, Chinese, and Russian. The HazMat test there is English only.
- All eight free practice tests
- Illinois CDL practice test
- Texas CDL practice test
- Class A versus Class B
Sources: 49 CFR 383.91: Commercial motor vehicle groups; 49 CFR 383.93: Endorsements; Texas DPS: How to apply for a commercial driver license; Illinois Secretary of State: CDL and CLP; New York DMV: Get a commercial driver license
Question counts: California's published table
The March 2008 California DMV evaluation, report RSS-08-225, is the document that prints a count. Table 1 lists the number of questions and the number of errors still allowed for a passing score on the forms DMV evaluated then. The report says each test had three forms. It is an evaluation of those forms, not a specification for the test you will be handed in 2026. California's current CDL page does not publish a replacement count. It does say you get three attempts on each required knowledge test per application.
| Test | Questions | Errors allowed |
|---|---|---|
| General Knowledge | 50 | 10 |
| Combination Vehicles | 15 | 3 |
| Air Brakes | 20 | 3 |
| Passenger Transport | 20 | 4 |
| Doubles/Triples | 15 | 3 |
| Tank Vehicle | 15 | 3 |
| Hazardous Materials | 20 | 4 |
Eighty percent of 50 is 40, so 10 errors allowed on that General Knowledge form matches the federal percentage. Four errors on a 20-question form is also 80 percent. Do not copy these lengths onto Texas, New York, Florida, Illinois, Pennsylvania, or Maine. Their pages, as checked for this guide, do not print a question count.
Sources: California DMV: Statewide evaluation of CDL written knowledge tests (March 2008); California DMV: Commercial driver licenses; 49 CFR 383.135: Passing knowledge and skills tests
Retakes
49 CFR 383.133 says states use the FMCSA pool and that an applicant who fails must be retested with a different version. Memorizing the order of answers on one sitting is a weak plan for that reason. California stops the application after three failures of the same knowledge test. Pennsylvania's Knowledge Test Authorization lasts one year and allows three tries on that authorization. Fees for another try, where a state prints them, are on the cost and timeline guide.
Sources: 49 CFR 383.133: Test methods; California DMV: Commercial driver licenses; Pennsylvania DMV: CDL learner's permit FAQs
A seven-session study plan
We do not have a sourced list of the topics people miss most often, so this page does not invent one. The study plan we do publish is a workflow: use your state manual, keep an error log, and spread the work across seven sessions you can repeat. It is not a seven-day guarantee.
- Collect the current manual and take a short baseline set.
- Study one weak General Knowledge topic and start the error log.
- Review that topic, then add a second one.
- Move to the next subject your agency lists, such as air brakes or combination vehicles.
- Keep the next required subject in its own notes.
- Mix the subjects and explain why an answer fits.
- Compare the log with the manual and pick the next cycle.
The full version, with a 30-minute session layout, is how to study for the CDL permit test. Official sample questions, when a state publishes them, are a useful extra. California posts commercial sample tests. Washington DOL posts a free 20-question practice test.
Sources: California DMV: Sample driver license knowledge tests; Washington DOL: CDL practice test
Questions from this page
What score do I need to pass?
49 CFR 383.135 says you must correctly answer at least 80 percent of the questions on each knowledge test. Failing air brakes adds an air-brake restriction if a permit or license is issued. Failing the combination test blocks a Class A permit or license.
How many questions are on the permit test?
The federal rule does not set one number. California's March 2008 evaluation, Table 1, lists 50 General Knowledge questions with 10 errors allowed, 20 air-brake questions with 3 errors allowed, and 15 combination questions with 3 errors allowed. That report is not a 2026 form specification. Other states in our sourced set do not publish a count.
What happens if I fail?
49 CFR 383.133 says a retake uses a different version of the test. California allows three attempts on each knowledge test per application. After three failures of the same test, that application is no longer valid. Pennsylvania's Knowledge Test Authorization allows three tries and is good for one year.
Sources and editorial notes
Editorial attribution: Evergreen Comply, LLC Editorial Staff. Each section links the official page the statement comes from. These pages do not replace your state manual, a registered training provider, or instructions from your licensing agency.
- 49 CFR 383.135: Passing knowledge and skills tests
At least 80 percent on each knowledge test. Failing air brakes requires an air-brake restriction if a CLP or CDL is issued. Failing the combination-vehicle test blocks a Group A CLP or CDL. - 49 CFR 383.133: Test methods
Knowledge tests come from the FMCSA pool. A retake uses a different version. Skills tests are in English, in this order: pre-trip inspection, basic vehicle control, on-road skills. - 49 CFR 383.93: Endorsements
H, N, and double/triple trailers are knowledge tests. P and S are knowledge and skills tests. A CLP may carry only P, S, and N. - 49 CFR 383.91: Commercial motor vehicle groups
Group A is a combination with a GCWR of 26,001 pounds or more if the towed vehicle is over 10,000 pounds GVWR. Group B is a single vehicle of 26,001 pounds or more GVWR, or that vehicle towing a vehicle not over 10,000 pounds. A driver who passed Group A tests may operate Group B or Group C vehicles with the required endorsements. - California DMV: Statewide evaluation of CDL written knowledge tests (March 2008)
RSS-08-225, March 2008. Table 1, re-read from the PDF on November 1, 2026. It describes forms used then. It is not a 2026 test specification. The live CDL page does not publish a current question count. - California DMV: Commercial driver licenses
Checked November 1, 2026. CLP steps, a 14-day hold, three knowledge-test attempts, an application valid for 12 months, and a CLP valid up to 180 days. California has paused non-domiciled CLP and CDL issuance until further notice. - Texas DPS: How to apply for a commercial driver license
Checked November 1, 2026. English-only knowledge tests as of June 1, 2026. Test order: Texas Commercial Rules, General Knowledge, Combination for Class A, Air Brake if applicable, then endorsements. CLP hold of 14 days. Application form CDL-1. Medical self-certification is CDL-4, CDL-5, or CDL-10. - Illinois Secretary of State: CDL and CLP
Checked November 1, 2026. Age 18 for intrastate, 21 for interstate or passengers. CLP is valid one year. Hold it at least 14 days before skills testing. Written tests: General Knowledge, Combination for Class A, Air Brake if the vehicle is so equipped, and endorsements. Only N, P, and S may be on a CLP. H and X need a TSA clearance before hazmat testing and are not allowed on a CLP. The page says to pay the appropriate fee. It does not print the dollar amounts. - Pennsylvania DMV: CDL learner's permit FAQs
Checked November 1, 2026. Apply with DL-31CD and self-certification DL-11CD. Non-excepted drivers submit a medical examiner's certificate. A Knowledge Test Authorization is valid for one year and allows three tries. PennDOT requires 15 days from permit issuance until the scheduled date of a Class A, B, or C skills test, and three tries on that permit for the skills test. The FAQ does not publish a dollar fee. - New York DMV: Get a commercial driver license
Checked November 1, 2026 on the live page. Permit application fee $10 for written tests taken together. Additional $5 for a required test not taken and passed then. Road test fee $40. Written tests for Class A, B, and C and endorsements are in English, Spanish, Chinese, and Russian. HazMat is English only. A road-test appointment cannot be scheduled for a date within 14 days of permit issuance.
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