What is the passing score on the CDL permit test?
Eighty percent on every knowledge test, set by federal rule. What that means in questions, and why the skills test is scored differently.
The passing score on every CDL knowledge test is 80%. That is not a state choice. Federal rules in 49 CFR 383.135 require a score of at least 80 percent on each knowledge test before a state may issue a commercial learner's permit or add an endorsement. A few states ask for more on one particular test, never less.
What 80% means in questions
| Test | Questions | You need | You can miss |
|---|---|---|---|
| General knowledge | 50 | 40 | 10 |
| Air brakes | 25 | 20 | 5 |
| Hazardous materials | 30 | 24 | 6 |
| Combination, tanker, doubles/triples, passenger, school bus | 20 each | 16 | 4 |
Each test is scored on its own. A perfect air brakes score does not help a weak general knowledge score, and failing one test does not undo the others. If you take three tests in one sitting and fail one, you come back for that one only.
Why 80% is harder than it sounds
Most people reading this passed their car licence test with a few days of study. The CDL knowledge test is different in two ways. The manual is long: Section 2 alone, which general knowledge is drawn from, runs to around 50 pages of rules and numbers. And the questions are specific. They do not ask whether you should check your tyres; they ask for the minimum tread depth on a steer tyre (4/32 of an inch) and on the others (2/32).
Drivers who fail usually fail by two or three questions. They knew the material in general and lost the points on numbers: following distance, air pressure, brake lag, tyre tread, the alcohol limit, how far from a railroad crossing to stop. Those numbers are a small share of the manual and a large share of the test.
Scoring in practice sets
The useful habit is to score yourself the same way the state will: 80% per test, not an average across topics. If you are passing general knowledge mock exams at 88% but air brakes at 72%, you are not ready, however good the average looks. PassRig's mock exams use the real question count and the 80% line for each test, so a pass in the app is the same bar as the one at the office.
How the skills test is scored
The skills test, taken later in the vehicle, is not a percentage. It has three parts: vehicle inspection, basic control skills and the road test. Each part is scored by the examiner against a list of items, and each has its own automatic failures. Missing too many inspection items, hitting a cone or a boundary on the basic skills, or an unsafe act on the road fails that part. You must pass all three, and in most states you can retake only the part you failed. The vehicle inspection part has the most memorising; the knowledge tests do not cover it in detail.