The best cdl study guide is your own state's commercial driver manual, studied in this order: general knowledge first, then air brakes, then combination vehicles if you want Class A, and endorsements last. Every knowledge test needs at least 80 percent under federal rules (49 CFR 383.135, ecfr.gov), so the goal is to know each section well, not to skim all of them.
Quick answer
Start with general knowledge because everyone takes it and the other tests build on it. Air brakes comes next because nearly every truck and bus has them and it is the section our students at US Driving School find hardest. Save hazmat, tank, doubles and passenger for last, and only study the ones you will actually need.
Step-by-step: where studying fits in the CDL process
- Pick your class and endorsementsClass A for combinations such as tractor-trailers, Class B for single heavy vehicles, Class C for smaller passenger or hazmat vehicles.
- Study and pass the knowledge testsPassing them, with a medical certificate and a regular license, gets you a commercial learner's permit (CLP).
- Add endorsement testsPassenger, school bus and tank can go on a CLP. Hazmat cannot, and it needs a TSA security threat assessment.
- Train and waitFinish entry-level driver training (ELDT) with a provider on the FMCSA Training Provider Registry and hold the CLP at least 14 days.
- Take the skills testPre-trip inspection, basic control skills and a road test. The manual's inspection chapter is your study guide for the first part.
Which knowledge tests you need
| Test | Who needs it | Study priority |
|---|---|---|
| General knowledge | Everyone | First |
| Air brakes | Anyone driving a vehicle with air brakes | Second |
| Combination vehicles | Class A | Third, for Class A |
| Passenger (P) | Bus drivers | After the core tests |
| School bus (S) | School bus drivers (needs P too) | After passenger |
| Tank (N) | Liquid or gas tank loads | After the core tests |
| Doubles and triples (T) | Pulling more than one trailer | After combination |
| Hazmat (H) | Placarded hazardous materials (age 21+) | Last; ELDT for hazmat comes first |
Costs and timeline
Fees depend on the state. On their official fee pages in 2026, Texas DPS (dps.texas.gov) lists $25 for a CLP and $97 for a new CDL, and the California DMV (dmv.ca.gov) lists $100 for an original Class A or B application. Training prices are set by schools, and the medical exam price by the examiner.
How long to study for the CDL permit
No agency sets a study time. In our experience, adults who study about an hour a day are usually ready for general knowledge and air brakes in one to three weeks. Add a few days for each endorsement. You are ready when you pass mixed practice tests well above 80 percent several times in a row, not when you finish reading.
CDL study guide: what to study first, in order
- General knowledge: inspection, vehicle control, shifting, seeing and communicating, space and speed, hazards, emergencies, cargo, and alcohol and drug rules.
- Air brakes: the parts in the order air travels (compressor, governor, tanks, foot valve, brake chambers), then the pressure numbers and the leak checks.
- Combination vehicles (Class A): coupling and uncoupling, trailer air lines, the tractor protection valve and rollover risk.
- Endorsements you need, one at a time.
- Mixed review tests to practice switching between topics.
Write down every question you miss and why. Most people who fail already knew the topic but fell for a wording trap, such as minimum versus maximum or a number that is close but wrong.
CDL study guide PDF free: where to get it
You do not need to pay for a study guide. State agencies post their CDL manuals free online. Texas DPS, for example, offers the Texas Commercial Motor Vehicle Driver's Handbook free on its website. Download your own state's version, since the core is the same but state rules differ.
CDL study guide NJ and PA
- New Jersey: the NJ Motor Vehicle Commission (nj.gov/mvc) gives a 50-question general knowledge test plus separate endorsement tests, with 80 percent needed on each.
- Pennsylvania: PennDOT (pa.gov) lists 70 general knowledge questions for Class A and 50 for Class B and C, plus 25 for air brakes. Pennsylvania also uses a 15-day wait before the skills test instead of 14.
CDL study guide 2026: what changed
The big 2026 change is language. Texas DPS made all CDL and CLP knowledge tests English-only starting June 1, 2026, and the U.S. Department of Transportation announced English-only CDL testing on February 21, 2026. The federal regulation we checked on ecfr.gov in October 2026 still lets states give knowledge tests in another language without an interpreter, and the federal announcement did not give an effective date. Study from the English manual so test day wording is familiar.
CDL study guide app
You do not need a separate app. DMVZone practice tests run in your phone's browser, so you can do a ten-minute set on a break and review missed questions later.
FAQ
How long to study for the CDL permit?
No agency sets a time. Studying about an hour a day, most adults are ready for general knowledge and air brakes in one to three weeks. Add a few days for each endorsement.
What should I study first for the CDL?
General knowledge, then air brakes, then combination vehicles for Class A, then any endorsements.
What score do I need?
At least 80 percent on each knowledge test under federal rules. The number of questions depends on your state.
Is there a free CDL study guide PDF?
Yes. Your state's CDL manual is free on the agency's website and is the source the test questions come from.
Is air brakes really the hardest test?
Many of our students say so, because it is full of numbers and parts that do not exist in a car. Give it the most practice time.
Confirm the tests and fees for your state with your licensing agency and FMCSA (fmcsa.dot.gov). DMVZone is a study resource, not a government agency.
