The useful answer is not a universal number. It is the number of separate tests your CDL goal requires in your state.
FMCSA sets minimum standards, but each state develops and administers its own CDL knowledge tests. The basic knowledge test must contain at least 30 questions, and the federal passing standard for general and endorsement knowledge tests is at least 80%. Your state CDL manual controls the exact question count, retest rules, fees, languages, and local process.
Use the plan below to avoid two costly mistakes: studying a module you do not need, or arriving at the licensing office without preparing for one you do.
Build Your CDL Permit Test Plan
| Your goal | Core knowledge tests | Add when applicable |
|---|---|---|
| Class A tractor-trailer | General Knowledge + Combination Vehicles | Air Brakes; Tanker; HazMat; Doubles/Triples; Passenger or School Bus |
| Class B straight truck | General Knowledge | Air Brakes; Tanker; HazMat |
| Class B bus | General Knowledge + Passenger | Air Brakes if equipped; School Bus for a school bus |
| Hazardous-material tank vehicle | General Knowledge + Tanker + HazMat | Air Brakes and Combination Vehicles when required by the vehicle class |
This is a planning tool. Verify the exact list with your state licensing agency before scheduling.
Class A study order
- General Knowledge: inspection, safe driving, cargo, emergencies, and vehicle control.
- Air Brakes: system components, inspections, warning devices, and safe operation when your target vehicle uses full air brakes.
- Combination Vehicles: coupling, trailer air lines, rollover and jackknife prevention.
- Job-specific endorsements: add only the modules required by the freight or passengers you plan to carry.
Class B study order
Class B applicants normally skip Combination Vehicles, but every Class B plan is not identical. A dump truck with air brakes, a school bus, and a non-air-brake delivery truck create different test requirements.
Before studying, confirm whether the vehicle uses air brakes, carries passengers or schoolchildren, transports liquid or gas in a qualifying tank, or carries placarded hazardous materials. Those answers determine your additional modules.
Check your starting score
Do not book the permit test based on reading alone. Take the 10-question General Knowledge diagnostic first. It shows whether your baseline is strong enough to move on or whether you need focused practice from the complete 1,500+ question bank.
Start the Free General Knowledge Diagnostic →How Many Questions Can You Miss?
The allowed misses depend on the number of scored questions your state gives you.
| Questions on your state test | Correct answers needed at 80% | Maximum misses |
|---|---|---|
| 30 | 24 | 6 |
| 40 | 32 | 8 |
| 50 | 40 | 10 |
For another disclosed test length, multiply the count by 0.80 and round the required correct answers up. Do not rely on a website’s fixed count if your state manual says something different.
Convert the Count Into a Passing Plan
- Take a diagnostic without looking up answers.
- Group misses by topic, not just by question.
- Review the matching state-manual section.
- Practice that module again with different questions.
- Do not schedule based on one lucky result. The legal pass line is 80%; a repeatable 90% practice score gives you a sensible buffer for unfamiliar wording and test-day pressure.
Choose the next test by your license path:
Verify These Five Items Before Scheduling
- current test sections for your class and endorsements;
- exact question count and language availability;
- appointment or walk-in rules;
- retest waiting period and fees;
- documents required for the CLP application.
Start with your state page in CDL Guides by State, then confirm the details on the linked official licensing site.
Frequently Asked Questions
How many questions are on the CDL permit test?
There is no single national number. States create their own tests under federal standards. The basic knowledge test must have at least 30 items, but the actual count may be higher.
What score do I need to pass?
Federal standards require at least 80% correct on general and endorsement knowledge tests.
Does every Class A applicant take the same tests?
No. General Knowledge and Combination Vehicles are central to a typical Class A path, while Air Brakes and endorsements depend on the vehicle and job. States may add requirements.
Does every Class B applicant need Air Brakes?
Not every Class B vehicle uses full air brakes, but many do. If the jobs you want use air-brake-equipped vehicles, prepare and test in appropriate equipment so you do not unnecessarily limit your license.