CMI Passing Score 2026: Exactly What You Need to Pass

The Number: 75% on 100 Questions

The passing score for the Council-certified Microbial Investigator (CMI) examination is 75%. The exam is issued by the American Council for Accredited Certification (ACAC) through its CMI Certification Board and delivered by Kryterion, Inc. It consists of 100 multiple-choice questions, each with at least four answer options, to be completed in three hours. The exam is closed book and computer-delivered.

Taken at face value, 75% of 100 questions means 75 correct answers. There is one important caveat: ACAC does not publish how many of the 100 items are scored versus unscored. If a portion of the exam consists of unscored items, the raw number of correct answers needed could differ from a naive reading of 75 out of 100. Because you cannot tell which items are unscored, the safe strategy is to treat every question as if it counts and aim well above the threshold in your practice work.

If you are still deciding whether the credential is the right fit, our guide on what CMI certification is explains the scope, and how hard the CMI exam is puts the 75% bar in context.

How the 75% Cut Score Is Set

ACAC states that the passing score is established using the Modified Angoff method. This is a standard-setting approach in credentialing: a panel of subject-matter experts reviews each exam item and estimates the probability that a minimally qualified candidate would answer it correctly. Those judgments are aggregated into a cut score.

What this means for you in practical terms:

• The standard is criterion-referenced. You are measured against a defined level of competence, not against other candidates on your test day. There is no curve in which a strong cohort raises your bar.
• The standard is defined around the minimally qualified candidate. The exam is designed to separate people who can design, conduct and interpret microbial sampling regimens competently from those who cannot, not to rank top performers.
• Results are immediate. The handbook describes immediate electronic scoring and an emailed result, so you will not wait weeks to learn whether you passed.

Adaptive testing is not described in ACAC's materials. The handbook describes a fixed question set with randomized question and answer order, which means your neighbor at a testing center (or another candidate online) may see the same items in a different sequence.

Passing Score vs. Pass Rate: Two Different Numbers

Candidates frequently confuse the passing score with the pass rate. They measure different things, and mixing them up leads to bad conclusions.

The 88% figure comes from ACAC's 2025 Exam Pass Ratio report. Read it carefully before leaning on it:

• It reflects a very small sample: 25 CMI examinations.
• It includes retakes and state-licensing-only examinations, and the report does not disclose how many CMI sittings fall into either category.
• It therefore cannot be treated as a first-attempt success rate, and it cannot predict your individual result.
• No 2026 pass rate has been verified.

For the full breakdown of what the data does and does not show, see CMI Pass Rate 2026: What the Data Shows. Note also that some third-party prep sites claim ACAC does not publish CMI pass rates; the issuer's own 2025 report contradicts that claim.

What You Are Actually Scored On: Six Domains, No Published Weights

ACAC's approved chart (approved February 21, 2024) lists six exam domains for the CMI. The chart is the formal source and it controls. A shorter, undated handbook summary lists only five topics and omits Health & Safety as a separate domain, so rely on the six-domain chart. No separately labeled 2026 exam version has been verified.

ACAC does not publish percentage weights for these domains. That means no one can legitimately tell you which domain carries the most questions. Some third-party practice sites publish their own allocations, but those describe the publisher's practice materials, not the official exam. Because your 75% is calculated across the whole exam, a gap in any one domain can cost you.

For a deeper treatment of each content area, read CMI Exam Domains 2026: Complete Guide to All 6 Content Areas. One more nuance: ACAC's chart uses columns numbered 1 through 7 for subdomains. Those are not seven extra domains. The formal chart contains the exam objectives, while the handbook's study-guide pages are illustrative preparation guidance, not an exhaustive list of what can be tested.

Format and Test-Day Mechanics That Affect Your Score

Your 75% is earned under specific conditions. Knowing them removes avoidable risk.

Time and pacing

Three hours for 100 questions gives you roughly 108 seconds per question on average. That is generous for straightforward recall items but tighter for scenario-style questions that ask you to interpret sampling data or choose among methods. Practice with a timer so that pacing is automatic.

Delivery options

• Proctored testing center: Bring two government-issued IDs, including one photo ID.
• Online with video proctoring: You supply the computer, an approved webcam and a private location. ACAC specifies at least 2 Mbps upload and download speed, and phones and tablets are excluded.

Arrival time discrepancy

ACAC's Examinations page says to arrive 15 minutes early, while the candidate handbook says 30. The two issuer documents disagree, so plan for the earlier 30-minute figure and confirm in your scheduling confirmation. Calculator permission is unverified in the materials we reviewed, so do not assume one will be available; check with ACAC before test day. No separate practical assessment is described for the CMI.

Before You Can Sit: Eligibility, Application and Fees

You cannot simply register and take the exam. The CMI requires an approved application first, so the "passing score" is only the last gate. Full details are in CMI Requirements 2026: Eligibility, Prerequisites & How to Qualify. In summary, one of two pathways applies:

• A related two-year postsecondary degree, or an equivalent 15 qualifying college credits, plus at least one year of documented microbial sampling; or
• A high school diploma or GED plus two years of consulting experience in microbial sampling.

Related fields include microbiology, engineering, science, architecture and industrial hygiene. Candidates must demonstrate designing, conducting and interpreting microbial sampling regimens, and must submit four project sheets, applicable academic evidence and experience verification. ACAC's eligibility FAQ requires at least one full year of actual field experience regardless of college credits. No mandatory preparation course or minimum training-hour requirement is published.

Fees

The $100 processing fee is part of the $400 certification fee, not an additional charge. No separate member/nonmember fee schedule is published. For a fuller cost picture, see CMI Certification Cost 2026: Complete Pricing Breakdown. Because a retake costs just $100, failing once is financially recoverable, but it still costs you time and momentum.

Application timing: documented conflicts

ACAC's application page describes online forms, required email verifications, six months including the examination, and unanimous board approval, with the board meeting every four to six weeks. The candidate handbook instead describes 90 days, notarized forms and employer affidavits, and board meetings roughly every four weeks. These issuer discrepancies remain unresolved, so confirm current requirements directly with ACAC before you build a schedule. Our CMI exam dates guide covers scheduling considerations.

The Reference Library Behind the Questions

The CMI handbook lists a bibliography that anchors the content. These are bibliographic listings, not proof of an exam revision, and the study guide warns that its selected pages are illustrative: candidates need comprehensive knowledge of the reference texts.

The domain mapping in the right column is our own study aid, not an official ACAC crosswalk. Note that the OSHA guide appears in the bibliography, but the CMI study-guide section does not supply a specific section or page subset for it, so plan to know the respiratory-protection material as a whole. Health & Safety is its own domain on the official chart, and the respiratory references are the natural place to build that knowledge. For a structured plan built around these sources, use the CMI study guide and the one-page CMI cheat sheet for final review.

Sequencing Your Prep Around the Six Domains

Since official weights are unpublished, the sensible approach is even coverage with extra time on your weakest domain. One short sequencing model, tied to how the domains build on each other, looks like this:

Domains 3 and 4 deserve extra attention because they map most directly to the experience requirement, designing, conducting and interpreting sampling regimens, that the application itself demands. Keep a log of questions you miss and tag each to a domain; patterns will show you where to spend your remaining time. You can try practice questions here to benchmark yourself before committing to a test date.

After the Exam: Results, Retakes and Renewal

Because scoring is electronic and immediate, you will know quickly. If you pass, certification runs for two years. If you fall short, the retake fee is $100, and the sensible next step is to study the domains where you struggled rather than simply re-sitting.

Renewal and recertification credits

ACAC's Recertification Procedures specify 40 recertification credits (RCs) per two-year term: 10 for continued field activity and 30 for professional development, with attestation and retained documentation in case of audit, plus a current photo. The detailed procedure differs from the handbook's general 40-RC wording and from the program page's 20 professional-development hours per year; the discrepancy is preserved in the issuer's materials, so confirm the current rule with ACAC. Renewal costs $400.

If you are weighing the credential's career value, avoid relying on unsupported salary claims. No reliable salary survey specific to ACAC CMI holders, and no causal earnings premium, has been verified. Our ROI analysis and salary guide separate occupational compensation from evidence about certification value, and CMI jobs covers where the credential is used. ACAC's activity report as of December 31, 2025 lists 25 CMI applicants, 59 recertifications and 166 current certifications, which gives a sense of the size of the credentialed community; these are issuer counts, not search-volume or demand estimates.

Frequently Asked Questions

For a broader introduction before you start, see What Is CMI? and CMI training options, then check this passing-score reference again as ACAC updates its materials.