CDL Hazmat Endorsement Knowledge Test Pass Rate, Format & Study Guide

The CDL Hazmat (H) endorsement knowledge test is the written test for the hazardous materials endorsement on a commercial driver's license. The knowledge standards are set federally by the Federal Motor Carrier Safety Administration (49 CFR Part 383) and the test is administered by each state driver licensing agency. The number of questions and any time limit are set by your state; this portal's practice mock has 30 questions, the length commonly described in state CDL guides.

Under 49 CFR 383.93, the H endorsement applies to vehicles used to transport hazardous materials as defined in 49 CFR 383.5, and it requires a knowledge test. Passing the knowledge test is a required step before the state issues the endorsement.

Commercial drivers preparing for the hazmat (H) endorsement and candidates retaking the knowledge test. State procedures and fees vary; check your state licensing agency before you apply.

The certifying body does not publicly publish an official pass rate for this exam. Be wary of third-party sites citing a specific number here — treat any pass-rate claim you see elsewhere for this exam as unverified.

Your state licensing agency sets the retake rules, fees and any waiting period after a failed knowledge test; check the agency before you reschedule.

Passing standard: Federal rule 49 CFR 383.135 requires you to answer at least 80 percent of the questions correctly on a CDL knowledge test. The number of questions and any time limit are set by your state; this portal's practice mock has 30 questions, the length commonly described in state CDL guides. No official pass rate for this exam was available in the sources we reviewed, so none is quoted here.

The number of questions and any time limit are set by your state; this portal's practice mock has 30 questions, the length commonly described in state CDL guides. Format: State-administered knowledge test · federal minimum score 80% · this portal's practice mock: 30 questions. Passing standard: Federal rule 49 CFR 383.135 requires you to answer at least 80 percent of the questions correctly on a CDL knowledge test.

• Hazardous Materials Regulations37%
• Hazardous Materials Handling33%
• Operation of Emergency Equipment15%
• Emergency Response Procedures15%

The content outline spreads questions across 4 areas: Hazardous Materials Regulations (37.0%); Hazardous Materials Handling (33.0%); Operation of Emergency Equipment (15.0%); Emergency Response Procedures (15.0%).

You need a commercial driver's license or commercial learner's permit, and the H endorsement also requires a federal security threat assessment (background check) before it is issued; confirm the current steps with your state licensing agency.

Knowledge test and endorsement fees are set by each state; the federal security threat assessment required for the H endorsement has its own separate fee. Check your state licensing agency for the current testing, endorsement and background-check fees.

After you are endorsed, the H endorsement has its own renewal and security threat assessment schedule set by your state and TSA; check your state agency for the current rules.

Start with the heaviest areas of the content outline: Hazardous Materials Regulations (37.0%); Hazardous Materials Handling (33.0%); Operation of Emergency Equipment (15.0%). Then work through the remaining areas, practise jurisdiction-specific rules separately from the general content, and finish with timed full-length practice runs of 30 questions in one sitting.

Content outlines, fees and passing standards change; this guide follows the materials listed under Verification as of October 2026. Check the licensing authority and test administrator before you register.