- The Number: 75% on 100 Questions
- Why 75%? The Modified Angoff Method
- How the Exam Is Built and Delivered
- What 75% Looks Like in Practice
- Where Your Points Come From: Seven Competencies
- The Reference Shelf Behind the Questions
- Reading ACAC's Pass Statistics Carefully
- A Domain-Ordered Prep Schedule
- Fees, Retakes and What a Miss Costs
- FAQ
- The Council-certified Residential Mold Inspector exam requires a 75% score on 100 multiple-choice questions.
- You get three hours, closed book, with at least four answer choices per question.
- Results arrive immediately on screen and by email through Kryterion, in a center or by online proctoring.
- A retake costs $100, while the full first-time cost is $500 ($100 exam plus $400 certification).
The Number: 75% on 100 Questions
The Council-certified Residential Mold Inspector (CRMI) credential, awarded by the American Council for Accredited Certification (ACAC), uses a passing score of 75%. The exam contains 100 multiple-choice questions, so the practical target is 75 correct answers. There is no published scaled-score conversion, and nothing in ACAC's public materials suggests that individual questions carry different point values. Treat the exam as a straightforward 75-of-100 hurdle.
One identity note before going further. This article covers the ACAC credential only. The same four-letter abbreviation is used for other, unrelated credentials, including a similarly abbreviated course credential from the Professional Mold Inspection Institute (PMII). Their exams, fees and scoring rules do not apply here. If you are comparing programs, our guide on what CRMI certification is explains the disambiguation in more detail.
Why 75%? The Modified Angoff Method
ACAC states that the passing score was established using the Modified Angoff Method. In general terms, this is a criterion-referenced approach: subject-matter experts review each question and judge how a minimally qualified candidate would be expected to perform on it. Those judgments are combined into a cut score. Candidates are not graded on a curve, and your result does not depend on how other people in your testing window performed.
Two practical consequences follow:
- The bar reflects competence, not ranking. A strong cohort does not raise the cut score, and a weak cohort does not lower it.
- The standard targets a minimally qualified inspector. Questions are written around what a practicing residential mold inspector needs to know to avoid harming clients or drawing unsupported conclusions.
For a sense of how demanding that standard feels, see our breakdown of how hard the CRMI exam is.
How the Exam Is Built and Delivered
| Feature | CRMI Detail |
|---|---|
| Question count | 100 multiple-choice questions |
| Answer choices | At least four per question |
| Time limit | Three hours for the written examination |
| Reference materials | Closed book |
| Passing score | 75%, set with the Modified Angoff Method |
| Question order | Randomized, with randomized answer order |
| Results | Immediate electronic results plus an emailed copy |
| Testing provider | Kryterion, Inc., at authorized centers or by secure online video proctoring |
Three hours for 100 questions gives you roughly 108 seconds per item, which is generous for recall questions but tighter for scenario-based items that ask you to weigh sampling results or choose a protocol. Randomized order means you cannot rely on a predictable sequence of topics, so build a flexible mental map rather than memorizing in a fixed order. The three-hour limit applies to the written exam only. It does not cover the application process, project sheets or document review that come first.
Because the exam is closed book, you cannot look up an exposure pathway, a calibration step or a remediation containment principle. Everything has to be retrievable from memory. If you are planning around calendars and windows, our CRMI exam dates guide covers scheduling logistics.
What 75% Looks Like in Practice
Because the score is simply 75 of 100, it helps to translate that into a working plan rather than a vague aspiration.
- Set your practice target above the line. If your practice scores hover right at 75%, your real exam result could land on either side. Aim for a consistent buffer on original, unfamiliar questions.
- Audit by competency, not just by total. A 78% total can hide a 55% in sampling design or data interpretation. Weak spots matter because the exam draws from all seven competency statements.
- Distinguish recall errors from reasoning errors. Missing the name of a fungal toxin is a recall problem. Choosing an unsupported conclusion from a set of spore counts is a reasoning problem. The second kind is more common in inspector-level exams and takes longer to fix.
Key Takeaway
Do not chase a perfect score. Chase a reliable margin over 75% across every competency, because one neglected area can cost more points than a handful of hard questions elsewhere.
Where Your Points Come From: Seven Competencies
ACAC publishes seven competency statements that describe what the exam tests. These are unweighted. ACAC does not publish percentage weights, so you should not assume that any one area is worth a fixed share of the 100 questions. Prepare for all seven. Our complete guide to all seven CRMI content areas goes deeper on each one.
Domain 1: Scientific knowledge of the morphology and ecology of specific biological agents
The biological-agent scope is broad: bacteria, fungi, amebae, viruses, dust mites, endotoxins and other bacterial cell-wall components, fungal toxins, glucans, antigens and microbial volatile organic compounds.
- Know how organisms are structured and where they thrive indoors.
- Separate the organisms themselves from the compounds they produce or carry.
- Expect questions that tie ecology (moisture, substrate, competition) to what you would find in a building.
Domain 2: An understanding of the health effects and risks associated with bioaerosol exposure
This area asks you to connect agents to exposure routes and health concerns without overstating causation.
- Understand how airborne biological particles reach occupants.
- Recognize the limits of what an inspector can say about health outcomes.
- Know when a concern belongs with a medical or industrial hygiene professional.
Domain 3: The ability to conduct microbial investigations, including the general principles governing their design and execution
Investigation design starts before any sample is collected.
- Frame the question the investigation must answer.
- Use visual and moisture-source assessment to direct the work.
- Understand how objectives shape scope, documentation and reporting.
Domain 4: The ability to design and execute appropriate microbial sampling regimens
The sampling competency covers strategy design, technologies, calibration, limitations and effective protocols.
- Match the sampling method to the question being asked.
- Know why calibration matters and what happens when it is skipped.
- Be able to state what each technique cannot tell you.
Domain 5: The ability to analyze sampling data accurately
This is the mechanical side of results: reading lab output correctly.
- Handle units, counts and comparisons without arithmetic slips.
- Understand how sampling conditions affect numbers.
Domain 6: The ability to evaluate and interpret sampling data responsibly
Analysis tells you what the numbers are. Interpretation tells you what they justify.
- Avoid conclusions the data cannot support.
- Account for variability, controls and outdoor comparison.
- Recognize when results are inconclusive rather than forcing an answer.
Domain 7: The ability to execute or recommend appropriate prevention, control, and remediation measures in cases of microbial contamination indoors
The exam expects practical, defensible recommendations.
- Connect moisture control to long-term prevention.
- Understand containment and protection principles during remediation.
- Know the role of respiratory protection in worker safety.
Notice the split between Domain 5 and Domain 6. Candidates who are comfortable with numbers often lose points on interpretation, where the best answer is the cautious one that stays within the evidence.
The Reference Shelf Behind the Questions
ACAC's study guide organizes preparation under five reference headings. These are preparation categories, not additional official domains and not a guarantee of exhaustive coverage:
- AIHA, Field Guide for the Determination of Biological Contaminants (second edition, 2005)
- ACGIH, Bioaerosols: Assessment and Control (first edition, 1999, or the study guide's alternative second-edition mapping, 2024)
- IICRC S500 (water damage restoration)
- IICRC S520 (mold remediation; S520-2015 with R520-2015, third editions, or S520-2024, fourth edition)
- NIOSH, Respirator Selection Logic (2004)
These references are not a numbered "2026 exam version." They are the published reading list, and the editions named above are what ACAC currently points candidates toward. Our CRMI study guide explains how to work through them without drowning in page counts.
Reading ACAC's Pass Statistics Carefully
ACAC's Accredited Certification Activity report, dated December 31, 2025, lists a 60% CRMI examination pass ratio for 2025, five applicants that year and 53 current certifications. A separate ACAC pass-ratio document has been attributed in prior review to three passes from five exam administrations, though that PDF could not be re-fetched for this article, so treat the administration-level detail as secondary.
Be disciplined about what these numbers can and cannot tell you:
- The sample is very small. With five applicants in a year, a single result moves the percentage dramatically.
- Applicants are not administrations. Do not treat an applicant count as the number of exam sittings.
- The applicant count includes state-license-only applicants, so it does not represent a clean pool of people pursuing the full ACAC credential.
- It is not a first-attempt probability. A 60% annual ratio says nothing reliable about your personal odds.
For the fuller picture, read our analysis of the CRMI pass rate. Use these numbers as context, not as a prediction.
A Domain-Ordered Prep Schedule
Rather than a generic weekly template, sequence your study so each competency builds the vocabulary needed for the next. This is one reasonable ordering, not an official plan.
Biology and exposure (Domains 1 and 2)
- Build your agent inventory: fungi, bacteria, viruses, amebae, mites and the compounds they produce.
- Pair each agent with where it lives indoors and how people encounter it.
Investigation and sampling design (Domains 3 and 4)
- Practice stating the question first, then choosing the method.
- Memorize limitations of each sampling technology, including calibration needs.
Data and interpretation (Domains 5 and 6)
- Work scenario problems where the correct answer is "the data do not support that conclusion."
- Drill unit handling and outdoor-versus-indoor comparison logic.
Prevention, control, remediation, then full review (Domain 7)
- Cover moisture control, containment and respirator selection logic.
- Finish with timed mixed sets under closed-book conditions.
Interleave timed practice questions from week three onward. You can build that habit with the CRMI practice test, and keep our CRMI cheat sheet handy for final-week review.
Fees, Retakes and What a Miss Costs
| Item | Cost (USD) |
|---|---|
| Examination | $100 |
| Certification | $400 |
| Total initial cost | $500 |
| Retake | $100 |
| Renewal (every two years) | $400 |
A failed attempt costs you $100 for the retake plus the time to close your gaps, which is modest compared with the full certification fee. That said, the exam is only one step. Eligibility requires a qualifying two-year postsecondary degree (or equivalent 15 credit hours in a relevant scientific or technical field) plus at least one documented year of residential mold inspection involving microbial sampling. The alternative path is a high-school diploma or GED with at least two years of qualifying consulting experience. You also submit four project sheets, educational records and experience verification for application review and certification-board approval. A preparatory course is not compulsory.
Details on the application window vary across ACAC materials: the current online application gives six months, while the handbook retains 90-day and notarized-paper wording. Confirm the operative deadline with ACAC directly. For the full eligibility picture, see CRMI requirements, and for budgeting, our CRMI certification cost breakdown.
Certification is valid for two years. Current renewal procedures require 40 recertification credits (10 for continued field activity plus 30 professional-development hours), with records retained for audit and a current photo. Whether the investment pays off depends on your market; our ROI analysis and salary guide evaluate that without assuming a proven CRMI-specific earnings premium.
FAQ
The passing score is 75%, which equals 75 correct answers on the 100-question multiple-choice exam. ACAC established the cut score using the Modified Angoff Method.
You have three hours for the written examination. The exam is closed book and delivered through Kryterion, either at an authorized testing center or by secure online video proctoring.
Results are provided immediately in electronic form and are also sent by email. Question and answer order is randomized, so your exam may not match another candidate's sequence.
You can retake the exam for $100. Use your result to identify which of the seven competency areas needs work, then retest after targeted review.
No. ACAC's 2025 figure comes from a very small group, includes state-license-only applicants in its applicant count, and is not a first-attempt probability. Your own preparation matters far more than that annual statistic.
No. This credential is certified by ACAC and is a CESB-accredited engineering-technician-level credential. Other programs with a similar abbreviation, such as PMII's course credential, are separate with different requirements. For training options, see CRMI training, and for career context, CRMI jobs.
The score you need is simple: 75 of 100. Getting there means treating all seven competencies as testable, reasoning conservatively about data, and building a margin before exam day. When you are ready to measure yourself, start with the full CRMI practice test site.