CTW Pass Rate 2026: What the Data Shows

The Pass Rate Reality: What ISA Does and Does Not Publish

If you searched for the ISA Certified Tree Climber pass rate hoping for a tidy percentage, here is the honest answer: the International Society of Arboriculture does not publish one in the issuer sources we reviewed. The program guide, the exam information page, the examination outline, and the common-questions table all describe what you must score to pass. None of them report how many candidates actually do.

That distinction matters, and it is the single most misunderstood point in this topic. A passing score is a threshold: the minimum performance you must demonstrate. A pass rate is an outcome statistic: the share of past candidates who cleared that threshold. ISA publishes the first and, as far as we can verify, not the second. For the exact thresholds, see our companion guide on the CTW passing score.

This article therefore does something different from most "pass rate" pages. Rather than inventing a number, it shows what the verifiable data does tell you: how the exam is built, where the structure creates risk, and what each failed attempt costs. Those facts are a better planning tool than any unsourced percentage.

Why a Single Pass Rate Would Be Misleading: Two Components

Even if ISA did publish a figure, a single number would blur two very different tests. The Certified Tree Climber credential has a computer-based or paper written examination and a separate outdoor skills assessment. Passing both is required unless an approved exception applies.

A candidate can be strong on one component and weak on the other. Someone with years in the canopy may know the work cold yet stumble on a question about terminology or standards. A person who memorized a study guide may know the theory yet freeze on a knot demonstration. Any blended statistic would hide exactly the information you need to prepare. The practical takeaway: treat these as two independent exams and prepare for each on its own terms.

Anatomy of the Written Exam: 65 Items, 50 Scored

The written exam contains 65 multiple-choice questions to be completed in 90 minutes. Of those 65, 15 are unscored pretest items that ISA uses to evaluate future questions. That leaves 50 scored questions. This is a subtraction, not an addition: it is not "65 scored plus 15 more." Some third-party practice sites describe the structure incorrectly, so verify against the issuer's program guide.

Because you cannot tell which items are unscored, you must treat every question as if it counts. The 80% written threshold applies to the scored portion. The exam is closed-book, phones and reference materials are prohibited, and breaks count against your time. We did not verify calculator or adaptive-testing policies, so do not assume either.

The five domains and where the points live

The current written exam is built on five weighted domains from the ISA Certified Tree Climber Examination Outline (2024 file, based on the 2022 job-task analysis). These weights describe the written exam only; they are not practical-station allocations and not chapters of any study book. For a deeper walkthrough, read our complete guide to all 5 content areas.

Do the arithmetic: Safety, Climbing and Rigging, and Removal together account for 70% of the written exam. A candidate who is thin in those three areas has little room to recover through the remaining 30%. This is the structural reason the written exam is more demanding than it first appears for people who climb every day but rarely think about formal standards.

Where Candidates Actually Fail: The Outdoor Skills Assessment

Because ISA does not publish outcome statistics, we cannot tell you which component produces more failures, and we will not pretend otherwise. What we can do is show you how the skills assessment is structured, because its scoring mechanics create specific, avoidable failure points.

Points and critical requirements

The skills assessment requires at least 70%, which means a minimum of 27 of 38 points, and all critical requirements satisfied. That second condition is the trap. You can accumulate enough points and still fail if you commit a critical failure. According to the 2024 Skills Test Evaluation Form, the assessment covers equipment inspection, six knot demonstrations at one minute per knot, critical failures, and tasks related to movable rope system (MRS) and stationary rope system (SRS) setups.

Timing: the climb clock

The work climb allows a maximum of 45 minutes. The clock starts at the first rope throw. There is a 30-minute full-credit target: exceeding it incurs a three-point timing deduction, and exceeding 45 minutes fails the task. Three points matters when your cushion is 11 points between the 38 available and the 27 you need. Preparatory equipment inspection and the knot demonstrations are separate from the timed climb, so do not confuse the 90-minute written limit, the 45-minute climb ceiling, and the 30-minute scoring target. They are three different clocks.

Competition waivers: narrower than they sound

ISA does offer an approved competition-based waiver, but it concerns the work-climb portion only. Completing all specified TCC or ITCC events, gear inspection, six knots, and evaluator documentation is still required. It is not a blanket waiver of the skills requirements, so do not plan around skipping the whole practical.

Why Third-Party Failure Percentages Do Not Hold Up

If you have seen a confident "X% of candidates fail" claim on a study site or forum, treat it with skepticism. We found no issuer source that supports third-party failure percentages for this credential. Several things make such figures unreliable:

• No official denominator. Without ISA publishing attempt and pass counts, any percentage is an estimate at best and an invention at worst.
• Two components. A figure that does not say whether it refers to the written test, the skills assessment, or the combined credential is meaningless.
• Reversed thresholds in older handbooks. Some older materials reverse the written and skills passing percentages relative to the current 80% written and 70% skills. A statistic built on those older numbers describes a different test.
• Anecdote bias. Candidates who post on forums skew toward those with questions, complaints, or nervousness, not a representative sample. Forum threads do show real demand for explanations about gear, knots, timing, and waivers, but they do not establish current rules.

The same caution applies to other claims you may encounter. At least one practice site describes 65 scored questions plus 15 unscored items and lists a $75 retake fee. Both conflict with the issuer's current guide, which gives 65 total items including 15 unscored, and a $120 retake fee. When a site gets verifiable structural facts wrong, its performance claims deserve even less trust.

The Filters Before Exam Day

One reason a pass rate would be hard to interpret even if published is that the credential has real prerequisites. Many unprepared people never reach the exam at all. To apply, candidates need:

• At least 18 months of arboricultural climbing experience, documented with appropriate employer evidence. Self-employed or business-owner applicants submit three references, which may be dated invoices, contracts, or business licenses documenting the climbing work.
• Current hands-on CPR and first-aid training, and physical aerial-rescue training, each completed within the preceding year.
• Agreement to ISA's ethics and credentialing requirements.

No mandatory academic degree or fixed training-hour total was verified. Note that enrolling in a training course is not the same as applying for the ISA exam; the application is a separate step with its own documentation. Full details are in our guide to CTW requirements. Because of this experience filter, the candidate pool is largely people who already climb for a living, which is a further reason raw failure percentages from other credentials should never be imported here.

For testing logistics, Pearson VUE physical testing centers deliver the computer-based written exam, with a 120-day authorization window and two required identification documents whose names match the application. A remote-proctored route was not verified. Scheduling specifics are in our exam dates guide.

What a Failed Attempt Costs

Even without a published pass rate, you can quantify the downside of failing. The numbers below come from ISA's current materials.

The $120 retake fee looks modest, but the 30-day wait is the bigger cost. If you fail the written exam, you lose at least a month of progress toward a credential you may need for a job, a promotion, or a certification-pay supplement. Whether the credential pays for itself is a separate question we address in our ROI analysis, where we separate occupation-wide tree trimmer wages from employer-specific incentives rather than claiming a universal premium.

Turning the Data Into a Readiness Plan

Without a pass rate to anchor your expectations, the most rational approach is to prepare against the structure itself. Since the weights are known, schedule your time in proportion to them. This is the one place where a study calendar earns its keep, and it is tied directly to the blueprint.

Two cautions on resources. First, the official Tree Climbers' Guide, Fourth Edition (2021), is a legitimate preparation publication, but ISA states that the book and the certification exams are developed through separate processes. Its chapters do not replace the examination outline and do not establish exhaustive exam coverage. Second, an original practice bank is useful for the written side, and our practice test maps questions to the five weighted areas, but a quiz score is not physical competency. Pair question practice with real rope time. For a compact refresher, the one-page cheat sheet is a handy final review.

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