- The Number: 75% on 100 Questions
- What 75% Means in Question Terms
- How the Board Sets the Bar: Modified Angoff
- Why There Is No Per-Domain Cut Score
- Exam Mechanics That Affect Your Score
- What Actually Earns Points Across the Seven Domains
- The 2025 Pass Ratio, Read Carefully
- If You Miss the Mark: Retake Mechanics
- Source Conflicts to Know Before You Apply
- Turning 75% Into a Study Plan
- Frequently Asked Questions
- The Council-certified Microbial Remediator exam has a 75% passing criterion, set by the ACAC CMR Certification Board using modified Angoff.
- The exam is 100 multiple-choice questions in three hours, closed book, with immediate results.
- ACAC publishes seven unweighted exam domains, so no domain percentages should guide your study allocation.
- The 2025 pass ratio of 31% (4 of 13) includes retakes and licensing-only exams, so it is not your odds.
The Number: 75% on 100 Questions
The passing criterion for the Council-certified Microbial Remediator (CMR) examination is 75%. The exam is administered through the American Council for Accredited Certification (ACAC), and the cut score is established by the CMR Certification Board rather than by the testing vendor. Kryterion, Inc. delivers the exam; it does not decide who passes.
Because the exam contains 100 multiple-choice questions, the arithmetic is simple: 75% corresponds to answering 75 questions correctly. That framing is a useful working target, and it comes with caveats covered below. If you are still deciding whether to attempt the credential at all, our guide to how hard the CMR exam is puts that threshold in context, and CMR requirements covers whether you qualify to sit for it.
What 75% Means in Question Terms
Candidates naturally ask whether they can miss 25 questions and still pass. Based on the published criterion, a 75% threshold on a 100-question exam implies that, but a few cautions apply before you treat "75 correct" as a guarantee.
- Confirm the scoring language in the handbook. The CMR Candidate Handbook is the governing document. The handbook is undated on the current web section, so verify its wording at the time you apply.
- Do not assume pretest or unscored items. The published materials we reviewed describe a 100-question exam and a 75% criterion; they do not describe how any unscored items would be handled. Plan as though every question counts.
- Results are immediate. Delivery includes immediate results, so you will not wait weeks wondering. That also means there is no partial-credit appeal process to plan around; plan to be ready on exam day.
The practical takeaway is to aim well above 75 on practice material rather than at it. Practice items written by third parties vary in difficulty and fidelity, so a score barely clearing the line on a question bank is thin evidence. You can calibrate against the style of the real exam with the CMR practice test on our main site.
How the Board Sets the Bar: Modified Angoff
ACAC states that the 75% criterion was set by the certification board using the modified Angoff method. In general terms, Angoff-style standard setting asks subject-matter experts to judge, item by item, how likely a minimally qualified candidate is to answer correctly, then combines those judgments into a cut score. The method exists to tie the passing standard to the competence the credential is meant to certify instead of to a curve against other test takers.
Two implications follow for you:
- Your result does not depend on how others perform. A criterion-referenced standard means you are measured against the bar, not against that day's cohort.
- The bar reflects practitioner judgment. Questions are written to separate someone who can safely scope, run and verify a microbial remediation project from someone who cannot. Memorizing isolated facts without understanding application tends to underperform.
Why There Is No Per-Domain Cut Score
ACAC's scope document, CMRS and CMR Examinations (approved February 21, 2024), lists seven examination domains. It is an unweighted chart: no percentage weights are published, and the numbered subdomain columns are not weights. The published criterion is a single 75% on the exam overall.
That has real consequences for how you study:
- You cannot compute a "safe" domain to neglect. Without published weights, any claim that one domain is worth a specific share of questions is invented.
- Be cautious with third-party sites that assign percentages to topic areas. Some question-bank providers publish their own five-topic breakdowns; those describe the provider's resources, not ACAC's seven domains.
- A strong domain can offset a weak one in the overall percentage, but because you cannot know how many questions come from each area, leaving any domain thin is a gamble.
For a domain-by-domain walkthrough, see our complete guide to all seven CMR content areas.
Exam Mechanics That Affect Your Score
Several delivery details influence how reliably you convert knowledge into a 75%.
| Feature | What the issuer publishes | Why it matters for scoring |
|---|---|---|
| Length | 100 multiple-choice questions | Each question is about one percentage point |
| Time | Three hours | Roughly 1.8 minutes per question on average, which leaves room to review |
| Choices | At least four answer choices per question | Distractors are written to be plausible; read all options |
| Reference use | Closed book | Standards, thresholds and definitions must be recalled, not looked up |
| Order | Randomized question and answer order | You cannot rely on a memorized sequence or "C is usually right" habits |
| Results | Immediate | You learn the outcome at the end of the session |
| Delivery | Testing center or online video-proctored | Online adds equipment and environment requirements |
Online proctoring requirements
Online candidates supply a computer, an approved webcam, a private location and a continuous 2 Mbps upload/download connection. A dropped connection or an environment problem can disrupt a session in a way that has nothing to do with your knowledge. If your home or office connection is marginal, a testing center may be the safer path to protect your score. Scheduling specifics are covered in our CMR exam dates guide.
What Actually Earns Points Across the Seven Domains
Because the exam is closed book and the handbook assumes comprehensive knowledge of the prescribed texts, the practical route to 75% is mastering the reference set and the seven domains together. The handbook's selected study pages are examples, not exhaustive coverage.
Prescribed references include:
- AIHA, Recognition, Evaluation & Control of Indoor Mold, second edition (2020)
- EPA, Mold Remediation in Schools and Commercial Buildings (2001)
- ANSI/IICRC S500-2021
- ANSI/IICRC S520-2015 with R520-2015, or S520-2024
- NIOSH, Respirator Selection Logic (2004)
Edition matters on a closed-book exam. When two editions of a standard differ, study the edition the handbook names and treat any other edition's numbers with suspicion. Note also that the shared issuer page lists OSHA bibliography entries that belong to the CMRS-only track; they are not part of the CMR reference list.
Domain 1: Principles & Equipment
Expect questions on how microbial growth works in buildings and on the equipment used to contain, filter and clean.
- Containment and negative-air concepts and when each applies
- Filtration and air-cleaning equipment and their proper use
- Moisture and its relationship to growth
Domain 2: Guidelines, Regulations & Standards
This domain rewards precise knowledge of the prescribed documents. The ACAC Code of Conduct sits within this domain; it does not create an eighth domain.
- What the EPA, AIHA and IICRC documents each recommend and where they differ
- Professional-conduct expectations for certified remediators
- Which document governs a given scenario
Domain 3: Water Damage
Water-loss categories, drying principles and the relationship between water events and microbial risk, anchored in ANSI/IICRC S500-2021.
- Classifying water losses and responding appropriately
- Drying goals and how progress is evaluated
Domain 4: Structural and Contents Remediation
Methods for removing or cleaning affected materials, and decisions about what can be restored versus discarded.
- Remediation approach by material type and condition
- Contents handling and cleaning methods
- Sequencing work to avoid cross-contamination
Domain 5: HVAC System Remediation
Why HVAC systems demand separate attention: they can distribute contamination building-wide, and their remediation has its own practices.
- Assessing and isolating HVAC components during work
- Cleaning approaches and their limits
Domain 6: Project Documentation & Verification
Scoping documents, records and the verification of completed work. This domain mirrors the project-sheet discipline you demonstrate in the application.
- What must be documented, and why
- How completion is verified
Domain 7: Safety
Worker protection including chemical safety and fall protection, which fall under this domain, and respirator selection logic from the NIOSH document.
- Respirator selection and its decision logic
- Chemical hazards on remediation sites
- Fall protection when working at height
For a structured review of these areas in order, use the CMR study guide, and keep the CMR cheat sheet handy for last-week recall.
The 2025 Pass Ratio, Read Carefully
ACAC's 2025 exam pass ratio report shows 31%, which is 4 passes out of 13 examinations. It is tempting to read that as "most people fail," but the number does not support that conclusion for you.
- The cohort is tiny. Thirteen examinations is too few to draw a stable rate; one or two outcomes would move the percentage substantially.
- It includes retakes. A candidate attempting for a second or third time counts again, which can depress the apparent rate.
- It includes state-licensing-only examinations. The report mixes exam uses, and passing a licensing-only exam does not itself confer the CMR designation.
- It is not a first-attempt probability. It cannot tell you your own chance of passing, which depends on your preparation and experience.
Key Takeaway
Treat the pass ratio as a signal that the exam deserves real preparation, not as a forecast. Our CMR pass rate analysis goes deeper on what the dated data can and cannot show.
If You Miss the Mark: Retake Mechanics
The cost structure softens the consequences of a miss. The initial US/Canada fee is USD 500, made up of USD 100 for the examination and USD 400 for certification covering the first two-year term. The current official application quotes USD 525 outside the US/Canada. A retake is USD 100. The certification fee includes a non-refundable USD 100 processing component, so confirm the refund terms before paying.
Because results are immediate, you know right away whether you passed, which lets you plan your next attempt while the questions are fresh. Use that window to write down the topics that felt shaky, then map them to domains and prescribed references. For the full fee picture, including optional course and book costs that are separate from issuer fees, see the CMR certification cost breakdown.
Source Conflicts to Know Before You Apply
The issuer's own pages are not perfectly aligned, and a few conflicts touch the process leading to your exam. None of them change the 75% criterion, but they can affect your timeline and paperwork.
- Application window: the current application page allows six months and online/email verification, while the handbook says 90 days and retains notarized-paperwork and employer-affidavit instructions.
- Board meeting cadence: the application page describes board meetings every four to six weeks; the handbook says approximately four weeks.
- Licensing wording: the application uses Florida mold-assessor wording, while the handbook's licensing paragraph says CMI. These inconsistencies do not change this remediation credential or establish its suitability for a particular license.
- Renewal hours: the issuer overview retains 20 professional-development hours per year, while current renewal procedures call for 40 RCs per two-year term: 10 for continued field activity and 30 for professional-development hours.
When sources conflict, follow the most current official instruction and, where it matters, ask ACAC to confirm in writing. Also note that the handbook is undated; the February 21, 2024 chart approval date does not establish a new 2026 exam version.
Turning 75% Into a Study Plan
Since no domain weights are published, a balanced plan that front-loads the reference documents and finishes with timed practice is the defensible approach. This is the one structured schedule in this article; adapt it to your experience.
Principles & Equipment, then Standards
- Read the AIHA indoor mold text and EPA remediation guidance, which underpin Domains 1 and 2
- Build a one-page list of which document says what
Water Damage and Structural/Contents
- Work through ANSI/IICRC S500-2021 for water-loss concepts
- Use S520 (the edition the handbook names) for the remediation methods in Domain 4
HVAC, Documentation, Safety
- Study HVAC isolation and cleaning limits
- Practice writing scopes and verification steps as you would on a project sheet
- Learn NIOSH respirator selection logic, chemical safety and fall protection
Timed, closed-book simulation
- Sit full-length 100-question sets in three hours
- Review every miss against the prescribed reference, not against an answer key alone
Scheduling safety last is deliberate: the NIOSH selection logic is a decision process that benefits from knowing the remediation scenarios it protects against. If you want help choosing a course or reference path, our CMR training overview compares how preparation options differ. A prep course is optional for certification, so choose based on your gaps.
Frequently Asked Questions
The passing criterion is 75%, set by the ACAC CMR Certification Board using modified Angoff. On a 100-question exam, that corresponds to roughly 75 correct answers, though you should confirm scoring language in the current handbook.
ACAC's published chart lists seven domains without percentage weights. The numbered subdomain columns are not weights, so avoid any source that assigns specific percentages to ACAC's domains.
No. The 2025 figure is 4 passes out of 13 examinations, a very small cohort that includes retakes and licensing-only exams. It is not a first-attempt success probability and cannot predict your result.
A retake costs USD 100. The initial US/Canada fee is USD 500 (USD 100 exam plus USD 400 certification for the first two-year term), and the certification fee includes a non-refundable USD 100 processing component.
No. The exam is closed book, with three hours for 100 multiple-choice questions and randomized question and answer order. Plan to recall definitions, standards and procedures from memory.
For a broader orientation to the credential and what it signifies, start with our CMR certification overview, and when you are ready to test yourself against exam-style questions, return to the CMR Exam Prep practice test.