ISA Exam Score Requirements and How Grading Works

Note: For the master overview, see our Complete ISA Certified Arborist Exam Study Guide.

You walk out of the testing center holding a piece of paper. It says "Pass" or "Fail." But what goes into that decision?

The Magic Number: 76%

To become an ISA Certified Arborist, you must achieve a score of 76% or higher.

• Total Questions: 200.
• Required Correct Answers: Approximately 152.

"Weighted" Questions?

The ISA uses psychometric analysis to ensure fairness. This means:

1. Pilot Questions: Some questions on your exam might be "ungraded" pilot questions (testing them for future exams). You don't know which ones they are, so treat every question as real.
2. No Partial Credit: You imply get the point or you don't.

Do I Have to Pass Every Domain?

No. This is a common myth. You do not need to get 76% in every single domain (like Soil or Pruning). You just need 76% overall.

• Example: You can get a 50% in Soil (your weak spot) as long as you get a 90% in Safety and Pruning to pull your average up.
• Strategy: Build a "Bank of Points" in the heavy domains (Safety/Pruning) to cover your losses in the hard science domains.

Interpreting Your Score Report

If you fail, the specific breakdown is critical for your retake.

• The report will list your percentage in each domain.
• Action: If you scored 40% in "Tree Biology," that is your mandate for the next 6 weeks. Ignore the domains where you scored 85%.

Retake Policy

If you don't pass:

1. One Free Retake: Most chapters (and the main ISA/Pearson route) offer one free retake within one year of your first attempt.
2. Waiting Period: There is no mandatory waiting period, but you need time to re-schedule.
3. Third Attempt: You usually have to pay a reduced administrative fee.

Summary

76% is a manageable bar if you respect the math. Don't be a hero in every category; just accumulate enough points to cross the line.