CIE Pass Rate 2026: What the Data Shows

The Official Number: 22 of 33

If you are searching for the Council-certified Indoor Environmentalist pass rate, there is one authoritative figure to anchor on. The American Council for Accredited Certification (ACAC) publishes a 2025 Exam Pass Ratio report, and for the CIE it lists 22 passes out of 33 examinations, with the printed percentage shown as 66%.

A small technical note: 22 divided by 33 works out to roughly 66.7%, but ACAC prints the integer 66%. When you cite this number, cite it the way the issuer prints it, and mention the underlying counts so readers can see how small the sample is.

For a broader walkthrough of how this number fits into overall difficulty, see our guide on how hard the CIE exam is.

What the Report Does and Does Not Measure

The single most common mistake in pass-rate articles is treating a published ratio as a personal probability. The ACAC figure supports a narrower set of conclusions.

What you can reasonably say

• In the 2025 reporting period, about two out of every three CIE examinations resulted in a pass.
• The sample is small (33 examinations), so a handful of results can move the percentage noticeably year to year.
• The exam is passable by a majority of those who sit it, but it is not a formality; roughly one in three examinations did not result in a pass.

What you cannot say

• It is not a first-attempt rate. The report counts retakes. A candidate who failed once and passed on a second sitting appears as one failure and one pass.
• It is not a 2026 rate. No 2026 CIE pass figure has been verified, and no separately labeled 2026 exam version was verified either.
• It is not limited to certification candidates. Examinations taken solely for state licensing are included, and those test-takers do not necessarily pursue the CIE designation.

Why the Bar Is 75 Percent and What That Implies

The CIE Certification Board sets the passing score at 75% using the Modified Angoff method. In Angoff-style standard setting, subject-matter experts estimate how a minimally competent practitioner would perform on each item, and those judgments are aggregated into a cut score. The result is a bar tied to a competence standard rather than to a quota, which means the pass rate is an outcome of candidate readiness, not a number ACAC steers toward.

On a 100-question exam, a 75% threshold means you need roughly three out of every four questions correct. ACAC does not publish how many questions are scored versus unscored, so do not assume that all 100 items count toward your result, and do not try to compute a precise "questions I can miss" figure.

The takeaway for pass-rate analysis is straightforward: because the standard is criterion-based, improving your preparation raises your personal chance of passing without changing anyone else's. You are not competing against a curve.

Who Is Sitting for the Exam

The CIE is not an exam people wander into. To be approved, applicants must meet one of two pathways:

• A related two-year postsecondary degree, or the equivalent of 15 qualifying college credits in engineering, science, architecture, industrial hygiene, or a related science field, plus at least one year of documented indoor-air-quality investigation experience; or
• A high school diploma or GED plus at least two years of that experience.

Applicants also submit four project sheets, academic evidence where applicable, and verifiable field experience. Academic credit does not eliminate the project documentation. The full eligibility picture is in our CIE requirements guide.

This matters for the pass rate because the candidate pool is pre-screened for field exposure. People reaching the exam have already documented real investigation work. That likely raises the baseline compared with an open-enrollment exam, but it also means a failure is more often a gap in a specific knowledge area than a lack of general familiarity.

One more caveat on the pool: because the report includes examinations taken only for state licensing, the 22-of-33 figure blends two groups with potentially different goals and preparation levels. A licensing-only pass does not authorize use of the CIE designation, and examination success alone does not complete board certification.

Where Candidates Likely Lose Points

ACAC does not publish per-domain pass rates or percentage weights, so any claim about "the hardest domain" or "the most heavily weighted domain" is speculation. What is published is the list of seven official examination domains, approved February 7, 2024. Because no weights are available, the safest strategy is balanced coverage, with extra time in the areas where your own field work has been thinnest.

Here is how to think about each domain as a risk surface for someone whose experience skews in one direction.

For a domain-by-domain breakdown with the official headings, read our complete guide to the seven CIE exam domains.

Exam Format, Fees, and Retake Math

Because the pass-rate report includes retakes, it helps to understand what a retake costs and how the exam is delivered.

The retake fee is modest, but a retake still costs time, rescheduling, and momentum. A full pricing breakdown is in our CIE certification cost guide. Optional preparation course charges and training-association membership discounts are separate from these issuer fees.

Remote-exam readiness

Online candidates supply their own computer, an approved webcam, and a private location, with at least 2 Mbps upload and download speeds. Phones and tablets are excluded. Testing-center candidates need two government-issued IDs, including one photo ID. ACAC's examinations page specifies arriving 15 minutes early, while the handbook specifies 30, so build in the longer window. Calculator permission is unverified, so do not plan around having one.

Timing details can also vary across issuer documents, so check our CIE exam dates guide and confirm directly with ACAC before booking.

Correcting the "No Public Pass Rate" Claim

Some third-party preparation sites state that ACAC does not publish a CIE pass rate. That claim is out of date or incorrect. ACAC's 2025 Exam Pass Ratio report does include a CIE line, and it prints 66%. If you are comparing prep providers, this is a useful credibility check: a provider that misstates what the issuer publishes may also be loose with other facts.

Similarly, practice-topic percentages shown on third-party sites describe that provider's own resources. They are not official exam weights. ACAC publishes no domain percentages for the CIE.

Also be careful with ACAC's own certification activity report. As of December 31, 2025, it lists 33 applicants, 161 recertifications, and 394 current CIE certifications. Those counts describe certification activity. They are not pass-rate data and should not be combined with the 22-of-33 examination figure.

A Domain-Ordered Plan Built Around the Numbers

Since roughly one in three examinations in the report did not result in a pass, and since no domain weights exist to prioritize by, the sound approach is to sequence your study by personal weakness and by how the listed references map to the domains. This is the only generic-method section in this article, so it stays tied to CIE specifics.

The study guide's page recommendations are not exhaustive exam coverage, so use the references as a foundation rather than assuming a reading list guarantees complete coverage. For a fuller approach, see our CIE study guide, and for a fast last-pass review, the CIE cheat sheet. When you are ready to pressure-test your knowledge, try questions on our CIE practice test site that mirror the multiple-choice format, and revisit weak areas before you sit the real exam.

Frequently Asked Questions