C-36 Exam Format: How Many Questions, Passing Score, and Time Limit (What CSLB Actually Says)

The California C-36 license takes two exams, the C-36 plumbing trade exam and the Law and Business exam, and you get 3½ hours for each. Both are closed-book, computer-based, multiple choice, with four choices per question and one BEST answer. Here is the part most websites get wrong: CSLB does not publish how many questions are on either exam, and it does not publish a passing percentage. Its own licensing guide says the percentage needed to pass "varies for each exam." Numbers you see quoted online, like "115 questions" or "72% to pass," are not CSLB's.

So the format is official and knowable. The question count and the cutoff are not. Study for the first and stop worrying about the second.

Key facts

How the C-36 exam is built

You sit for both exams on a computer at a PSI test center. CSLB says all exams are taken on a computer and consist of multiple-choice questions, and a short on-screen tutorial shows you how the system works before the exam starts.

The study guide adds the details that matter on the day:

• Four choices, one BEST answer. Questions are written to provide only one BEST answer. Two choices can look right; the job is picking the best one.
• Some math. Some questions require mathematical computation, and a calculator will be provided.
• Guess if you are stuck. There is no penalty for guessing, so never leave a question blank.
• Closed book. No reference materials may be used during the examination.

How many questions are on the C-36 exam?

CSLB does not say. The C-36 study guide, the Law and Business study guide, the exam FAQ and the Get Licensed to Build guide describe the sections, the weights and the rules, but none of them states how many questions are on either exam. If a site gives you a number, it is that site's number.

What CSLB does give you is better for studying: the weight of each section. The trade exam breaks down like this:

CSLB notes the percentages are approximate. Whatever the exact count is, the first two rows are close to half the exam.

What score do you need to pass?

CSLB does not publish one. In its Get Licensed to Build guide, the answer to "What percentage is needed to pass the exam?" is that applicants can ask CSLB, as the percentage "varies for each exam."

What you will see on the day:

• Pass: you are told you passed, but you are not given detailed information about your score. The pass report is not a license.
• Fail: the report shows your overall score, including the number of items answered correctly, and you see how well you did on each section. Those sections match the ones in the table above, so you know exactly what to study before the retake.

Since nobody can tell you the cutoff, the only safe target is not needing one: walk in having seen every section enough times that you are not guessing.

How long is the exam?

You get 3½ hours to complete each exam. The two exams are separate, each with its own fee, and you can schedule them on the same day or at different times. CSLB tells applicants to arrive 30 minutes before the scheduled exam time.

If you fail a part

Candidates who fail are eligible to retake the exam after 21 calendar days, as long as they are not past their 18-month void date. You only retake the exam you failed, because exam results are good for five years. You pay PSI each time you reschedule. All of it has to happen within the 18 months your application gives you to pass.

For every official rule in one place, see C-36 exam facts: what CSLB actually says.

Common questions

How many questions are on the C-36 plumbing exam?

CSLB does not publish a question count. None of its study guides, its exam FAQ, or its Get Licensed to Build guide states one. It does publish the weight of each section, which is the better thing to plan your studying around.

What score do you need to pass the C-36 exam?

CSLB does not publish a passing percentage. Its licensing guide says to ask CSLB, as the percentage "varies for each exam." Passing reports do not show a score; failing reports show your overall score and your results by section.

How long is the C-36 exam?

You get 3½ hours for the C-36 trade exam and 3½ hours for the Law and Business exam. You can schedule them on the same day or at different times.

Is the C-36 exam open book?

No. It is a closed-book examination, and no reference materials may be used. A calculator will be provided for the questions that need math.

Is the C-36 exam multiple choice?

Yes. Both exams are multiple choice with four choices per question, written to provide only one BEST answer, and taken on a computer at a PSI test center.

Sources

• CSLB License Examination Study Guide: Plumbing (C-36)
• CSLB License Examination Study Guide: Law and Business
• CSLB Examinations Frequently Asked Questions
• CSLB, Get Licensed to Build

_Last reviewed: 2026-10-15. Every fact above is quoted from the CSLB document it cites and checked by code against our stored copy of that document._

Practice the format before it counts

Take the free 21-question C-36 diagnostic: four choices, one best answer, and a written explanation for each question once you see your score. It shows you, topic by topic, where you would lose points today. No account needed. When you want the full course, it is $148.75 one time for lifetime access: lessons for both exams, practice questions with written explanations, and timed practice exams in the same closed-book, multiple-choice format. See what is included.