The CDL permit test has 50 questions on the general knowledge section

The Commercial Driver's License (CDL) permit test administered by your state's Department of Motor Vehicles contains 50 questions on the general knowledge exam. You must answer at least 40 of them correctly to pass — that is 80 percent. The test covers the rules of the road, safe driving practices, and vehicle operation as they explore to commercial trucks and buses.

This is the written exam you take before you can legally operate a commercial vehicle or practice with a CDL instructor. It is separate from the skills test (the driving portion) that comes later. The number of questions and passing score are set by federal regulation, so they are the same across all 50 states.

Key Takeaways

  • The general knowledge CDL permit test contains exactly 50 questions, and you need to answer 40 correctly to pass.
  • Additional endorsement tests (hazmat, tanker, doubles, passenger) each have their own question count and passing score, typically 20 to 30 questions.
  • You can retake the test the same day in most states if you fail, though some require a waiting period between attempts.
  • The test covers vehicle inspection, safe driving, braking systems, and cargo handling — not just traffic laws.

What the general knowledge test covers

The 50 questions on the general knowledge exam test your understanding of how commercial vehicles work and how to operate them safely. You will see questions about air brake systems, how to inspect a truck before driving, proper following distances at highway speeds, and how to handle skids or brake failure. The test also includes questions on federal regulations, hours-of-service rules, and what you can and cannot carry.

The questions are multiple choice with four answer options each. You answer them on a computer at the DMV testing center, and you receive your score when ready after you finish. If you pass, you get your CDL permit that day. If you do not pass, you can usually take the test again the same day or within a few days, depending on your state's rules.

Endorsement tests add more questions

If you need a CDL endorsement — such as for hazardous materials (hazmat), tanker vehicles, doubles/triples, or passenger transport — you take a separate test for each one. These endorsement tests are shorter than the general knowledge test. The hazmat endorsement test, for example, has 30 questions and requires a score of 24 (80 percent). The tanker endorsement has 20 questions and requires 16 correct.

You do not have to take all endorsements at once. Many drivers pass the general knowledge test first, get their permit, and then add endorsements later as their job requires. Each endorsement test is administered the same day at the DMV, so you can stack them if you want to.

How much time you have to complete the test

Most states give you 60 minutes to complete the 50-question general knowledge test. That works out to roughly one minute per question, though you can spend more time on harder questions and less on ones you answer quickly. The timer usually appears on the screen, so you can track how much time remains.

If you are taking multiple tests in one session — the general knowledge test plus one or more endorsements — the time limits are separate for each test. You finish one, submit it, and then the timer resets for the next one. This means you are not racing against a single clock for all your tests combined.

Preparing for the 50-question test

Your state's DMV publishes a CDL handbook that covers all the material on the test. The handbook is free and available online or in print at any DMV office. Reading through it once gives you the foundation, but most people study it more than once because the material is technical — air brake systems and cargo weight limits are not intuitive if you have never worked with trucks.

Many people use practice tests to prepare. These are not official, but they follow the same format and cover the same topics as the real test. Taking a practice test helps you identify which topics you need to study more and gets you used to the multiple-choice format and time pressure. Some practice tests are free online; others are paid apps or study guides sold by third parties.

What happens if you fail the test

If you score below 40 out of 50, you fail and do not receive your permit. You can retake the test, but the rules vary by state. Some states let you retake it the same day; others require you to wait 24 hours or longer between attempts. A few states charge a fee each time you take the test, while others charge only once per process period.

There is no limit to how many times you can retake the test, so failing does not lock you out of getting a CDL. However, each failed attempt costs time and sometimes money, so most people study the handbook and take a practice test or two before sitting for the real exam.

Frequently Asked Questions

Can I take the CDL test online from home?

No. The CDL permit test must be taken in person at your state's DMV testing center. The test is administered on a computer at the center, and a proctor watches to prevent cheating. You cannot take it remotely or on your own device.

Do all 50 states ask the same 50 questions?

No. The question bank is the same across all states, but each test pulls 50 questions randomly from that bank. Two people taking the test on the same day in the same state will see different questions, though they cover the same topics and difficulty level.

What if I fail one endorsement test but pass the general knowledge test?

You still get your CDL permit based on passing the general knowledge test. You can add the endorsement later by retaking just that endorsement test. You do not have to retake the general knowledge test.

Is the CDL test harder than the regular driver's license test?

Yes. The CDL test covers more technical material — brake systems, cargo regulations, and vehicle inspection — that most regular drivers never learn. The passing score is also the same (80 percent), but the questions require more specialized knowledge about commercial vehicles.

How long is the CDL permit valid after I pass the test?

Your CDL permit is usually valid for 180 days (six months) from the date you pass the test. During that time, you must pass the skills test to get your full CDL license. If the permit expires before you pass the skills test, you have to retake the written test.