How Hard Is the CHRN Exam? Complete Difficulty Guide 2026

So, How Hard Is It? The Honest Verdict

The Certified Hyperbaric Registered Nurse (CHRN) exam is best described as moderately difficult for prepared candidates and punishing for unprepared ones. It is not a test you can pass on general nursing instinct. Most of the nursing fundamentals you already know, such as assessment, medication safety and wound care, appear in only part of the scope. The rest is a technical body of knowledge that many hospital nurses have never studied: gas laws, decompression theory, chamber fire safety, transcutaneous oxygen monitoring and the operation of monoplace and multiplace chambers.

The good news is that the CHRN has a few structural features that work in your favor. The exam is entirely multiple-choice and true/false, with no essays or short-answer items. The passing threshold is a published 70%. And the issuer publishes its study-guide scope, so you know what you are walking into. The difficulty lies in covering a broad, unfamiliar domain thoroughly, not in trick questions or an opaque format.

If you want the full picture of how scoring works, see our companion piece on the CHRN passing score. For the broader landscape of what is tested, the complete guide to all 16 CHRN content areas breaks down each topic.

What the Exam Actually Looks Like

Understanding the format removes a lot of unnecessary anxiety. Here is what the current-linked June 2024 resource manual establishes:

Two hours for 120 items works out to an average of one minute per question. That is comfortable for recall questions but tight if several items require multi-step pressure conversions or gas-law calculations. Practice working through those calculations quickly with your calculator, because speed on the math is what protects your time budget for the clinical items.

Governance is split across two bodies. The Baromedical Nurses Association Certification Board (BNACB) oversees nursing eligibility and certification, while the National Board of Diving and Hyperbaric Medicine Technology (NBDHMT) administers and grades the testing. Testing is at approved centers, not default unproctored home testing.

The Real Gatekeepers: Prerequisites Before You Ever Sit

For many nurses, the hardest part of the CHRN is not the two-hour exam but qualifying to take it. The eligibility ladder is steep, and it is worth understanding before you decide how difficult the credential will be for you.

• Unrestricted RN license.
• Clinical experience: two years in a hospital or clinic setting, or one year of critical care.
• Recent hyperbaric experience: an active hyperbaric year.
• Approved training: a 40-hour introductory course, or applicable 40 Category A replacement credits.
• 480 post-course patient-care hours with qualified preceptor approval.
• Employer recommendation.

Note the distinction: the 40-hour course and the 480 experience hours are prerequisites, not part of the two-hour exam timer. By the time you register, you have already spent substantial time in a hyperbaric department. That is a built-in advantage. Candidates who have run real treatments, watched compression and decompression, and handled patient prep have a context that textbook-only learners lack. For a full walkthrough, read our guide to CHRN requirements and how to qualify, and see what introductory coursework involves on our CHRN training page.

Where Candidates Struggle: The Hardest Content Areas

The issuer's study guide covers sixteen technical preparation topics, and the sections below are the ones that most often separate comfortable passes from near-misses. Note that the study-guide topics are unweighted competencies in the source material, and no official percentage weighting has been verified. The ranking here reflects the nature of the material, not published exam weights.

The patient-protection material is where your nursing judgment meets hyperbaric physics. Questions often present a clinical scenario and ask what to do before compression, which rewards candidates who have internalized the pre-treatment checklist.

What We Know (and Don't) About Pass Rates

Candidates naturally want a pass rate to gauge difficulty. Here is the honest state of the evidence: a current CHRN-specific pass rate is not publicly disclosed. A historical combined-program figure of 74% has circulated, but it is not CHRN-specific and should not be treated as the pass rate for this credential. Anyone quoting a precise current CHRN pass percentage is either guessing or borrowing a number from somewhere else.

What you can say with confidence is that the threshold is 70% and that the format is objective. Our CHRN pass rate analysis goes deeper into what the available data does and doesn't support, and you can pair it with the passing score breakdown to understand how the 70% line translates to a target number of correct answers.

Two Gaps in the Published Scope You Should Plan Around

Honest difficulty assessment means flagging what is not known. Two gaps matter for your preparation:

1. No verified weighted blueprint. The June 2024 manual's study-guide contents list sixteen technical topics and thirteen detailed body sections, while its own introduction still says twelve sections. None of those counts is an authenticated exam-domain count, and current official percentage weights remain unverified. Do not assume that a topic with a long chapter carries proportionally more questions. Study all sixteen areas, and treat any site claiming exact domain percentages with skepticism.
2. Legacy clinical content in the manual. The manual contains older clinical narrative, including a reference to a 1992 indications report as the most recent, which is outdated. The UHMS Indications 15th edition front matter is dated 2023 and reflects updated indications and references. Use the manual to understand scope, but verify accepted indications, dosing and safety and nursing standards against current authoritative sources.

Also note that three of the sixteen listed topics (NFPA hyperbaric-chamber guidance, the BNA hyperbaric nursing standards of practice, and operation of monoplace and multiplace chambers) do not have separate detailed chapter bodies in the manual. You will need to pull these from the external standards themselves, most notably the NFPA guidance and the standards posted on the BNA website. This is a common blind spot for candidates who study only from the manual.

For a domain-by-domain scope list you can check yourself against, see the CHRN exam domains guide and keep the CHRN cheat sheet handy for last-week review.

The Money and Logistics Side of Difficulty

Exam difficulty is partly financial, because the stakes of a failed attempt include fees and time. According to the June 2026 initial application, exam fees are:

Membership evidence is required. The June 2024 manual lists US$100 for a repeat examination, and no newer retake-fee override was found in the retrieved initial application, so confirm the current repeat fee with the issuer before you plan around it. The application also directs you to register 30 days before the test, so last-minute scheduling is not an option. For a full cost picture including the 40-hour course and renewal, see our CHRN certification cost breakdown, and check testing windows on the CHRN exam dates page.

Long-term difficulty also includes maintenance. Renewal is every four years and requires an active RN license, employer or medical-director confirmation of at least one year of hyperbaric experience including 480 hours in the previous 12 months, and 40 CE hours including 20 Category A. The August 2025 renewal form lists fees of US$150 for BNA members, US$200 for UHMS or ACHM members and US$250 for nonmembers, and a lapse adds US$100 and removes member discounts. Passing the exam is the first hurdle, but staying certified also demands ongoing clinical practice.

A Difficulty-Weighted Study Sequence

You do not need an elaborate system, but you do benefit from sequencing the material by dependency. Physics and physiology underpin decompression, oxygen toxicity and safety, so they come first. Here is one logical ordering built around CHRN specifics:

Finish with timed practice. Try mixed sets under the two-hour constraint with the calculator beside you, so the pacing feels familiar. You can test yourself with our CHRN practice questions, and for a broader preparation framework see the CHRN study guide for first-attempt success.

Who Finds It Easier, and Who Finds It Harder

Typically easier: nurses who work daily in a hyperbaric department, have completed the 40-hour course recently, and have regularly handled patient prep, chamber checks and treatment tables. Critical care and wound care backgrounds map well onto the nursing-management and patient-assessment material.

Typically harder: nurses whose experience in the department is thin, who studied the introductory course long ago, or who struggle with unit conversion and applied physics. The math-heavy domains and the NFPA and facility-engineering content often feel foreign to candidates from purely bedside backgrounds.

If you are weighing whether the effort is justified, our ROI analysis of the CHRN and the CHRN jobs overview describe who hires hyperbaric nurses, while the CHRN salary guide covers earnings context. New to the credential entirely? Start with what CHRN certification is and what CHRN stands for.

The bottom line: the CHRN exam is fair and finite. The topics are published, the format is straightforward, and the real work is steady, structured coverage across sixteen unfamiliar areas. Candidates who respect the physics, verify their clinical content against current sources and practice under timed conditions give themselves every chance to clear the 70% threshold. Ready to test your readiness? Try the CHRN Exam Prep practice test.

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