The California CDL knowledge exam is really several exams in one, depending on which endorsements you need. Here's the real breakdown.
The real exam format
The core General Knowledge exam is 50 multiple choice questions, untimed. If you're pursuing air brakes, combination vehicles, passenger, school bus, tank, or HazMat endorsements, each of those is a separate additional knowledge test on top of the general one.
What score do you need to pass?
You need 40 out of 50 correct (80%) on the General Knowledge exam. Endorsement exams generally use the same 80% threshold, though the question count per endorsement varies.
How to pass on your first try
- Know exactly which endorsements you actually need before you study. Studying the wrong endorsement wastes real time — confirm with your employer or the specific job you're targeting first.
- Air brakes trips up more first-time test-takers than any other section if you've never driven an air-brake vehicle — the physical system and its failure warnings are conceptually different from hydraulic brakes, so don't skim it.
- Vehicle inspection procedures reward rote memorization of a sequence, not general knowledge — practice the actual walk-through order, not just the individual facts.
- Take a full practice exam per endorsement you're testing for, not just the general knowledge test — each one has its own distinct question style.
Free practice questions and a cheat-sheet-style breakdown
The California CDL track page has free sample questions covering general knowledge and every major endorsement, plus a full topic breakdown. The track's Resources tab also has quick-reference tables and flashcard decks — see what's in the California CDL Key Facts Digest.