- Which RMS This Sheet Covers
- Exam Facts at a Glance
- Test-Day Rules and Logistics
- The Six Subject Areas and Their Published Counts
- Topics to Master Before Exam Day
- Eligibility: Initial and Alternate Routes
- Fees, Renewal and CE Math
- What an RMS Is Allowed to Do
- Sequencing Your Review by Domain
- Source Caveats Worth Knowing
- Frequently Asked Questions
- The exam has 100 single-best-answer multiple-choice questions, 2 hours, and a 70% passing score.
- Analysis of Measurements (33) and Performance of Tests (30) carry the largest published subject counts.
- The exam costs USD 120, is nonrefundable, and must be taken on a personal desktop or laptop.
- A failed attempt can be retried after 14 days; a pass stays valid for your application for one year.
Which RMS This Sheet Covers
Several credentials share the letters "RMS," so settle this first. This cheat sheet covers the Radon Measurement Specialist credential issued by the National Radon Safety Board (NRSB). It is not the NRPP Radon Mitigation Specialist credential and not the NRSB's separate mitigation-side certification. Everything below concerns professionals who place radon testing devices, analyze the results, and sign the reports that clients rely on.
If you are still orienting yourself, start with What Is RMS Certification? or What Does RMS Stand For?, then return here for the condensed review. When you are ready to test yourself against realistic questions, the RMS practice test site is the logical next stop.
Exam Facts at a Glance
These are the numbers worth memorizing. They come from NRSB's published exam logistics, reviewed October 14, 2026.
| Item | Fact |
|---|---|
| Issuer | National Radon Safety Board (NRSB) |
| Delivery | Prolydian online delivery with a live virtual proctor, plus Proctor360 system requirements |
| Format | 100 single-best-answer multiple-choice questions |
| Time limit | 2 hours |
| Passing score | 70% |
| Exam fee | USD 120, nonrefundable |
| Retake wait | 14 days after a failed attempt |
| Result validity | A pass remains valid for a certification application for one year |
| Scheduling lock | Appointments cannot be cancelled or changed within 24 hours |
Seventy percent of 100 questions means you need 70 correct answers, which leaves room for 30 misses. For deeper context on that threshold, see RMS Passing Score 2026: Exactly What You Need to Pass. For scheduling mechanics, RMS Exam Dates 2026: Testing Windows, Deadlines & Scheduling covers the practical side.
Test-Day Rules and Logistics
Many candidates lose focus before the first question because of avoidable setup problems. Remember these requirements:
- Equipment: a personal desktop or laptop. A work computer or a mobile device is not acceptable.
- Proctoring: a live virtual proctor monitors you, and the linked Proctor360 system requirements must be met on your machine.
- Permitted materials: one sheet of scrap paper and a pen or pencil, plus the on-screen calculator, formula sheet, and digital notepad.
- Scheduling: no cancellations or changes within 24 hours of your appointment, and the USD 120 fee is nonrefundable.
Because the formula sheet and calculator are provided on screen, rote memorization of every equation matters less than knowing when and why a calculation applies. Run a system check well before your appointment, not on the morning of the exam.
The Six Subject Areas and Their Published Counts
The NRSB Certification Exams Study Guide lists six subject areas for the RMS exam. The guide's table reproduces counts for each area. Here they are in the order the guide lists them:
| Domain | Published Count |
|---|---|
| Domain 1: Problem Evaluation | 6 |
| Domain 2: Performance of Tests | 30 |
| Domain 3: Analysis of Measurements | 33 |
| Domain 4: Interpretation of Results | 11 |
| Domain 5: Report of Findings | 17 |
| Domain 6: Professional Standards of Conduct and Ethics | 3 |
Analysis of Measurements has the largest listed count at 33, followed by Performance of Tests at 30. Together, those two areas account for most of the listed total. The six counts sum to 100, matching the length of the exam.
For a domain-by-domain walkthrough, see RMS Exam Domains 2026: Complete Guide to All 6 Content Areas.
Topics to Master Before Exam Day
The blocks below organize what a measurement specialist needs to be fluent in, grouped by exam domain. They describe the kind of competence the exam rewards; they are preparation topics, not an official item list.
Domain 1: Problem Evaluation
Before any device is placed, a specialist must understand what the client actually needs measured and under what conditions.
- Clarifying the purpose of a test before choosing a method
- Recognizing building and occupancy factors that affect how a test should be set up
- Knowing when a situation calls for a different approach or further information
Domain 2: Performance of Tests
The second-largest published count, so field procedure deserves serious time.
- Device selection, placement, and retrieval practices
- Maintaining test conditions and documenting anything that could compromise a result
- Using approved devices with the applicable calibration and proficiency documentation
Domain 3: Analysis of Measurements
The largest published count. Expect calculation-flavored and data-handling questions here, where the on-screen calculator and formula sheet earn their keep.
- Working from raw device readings to reportable results
- Understanding how device type and quality assurance data affect confidence in a result
- Recognizing results that look wrong and knowing what to do about them
Domain 4: Interpretation of Results
Moving from a number to a defensible conclusion.
- Placing measurements in context rather than reading them in isolation
- Understanding the limits of what a given test can and cannot show
Domain 5: Report of Findings
The specialist signs the report, so accuracy and completeness are professional obligations.
- What a client report must contain and how findings should be communicated
- Linking documentation (devices, calibration, conditions) to the conclusions stated
Domain 6: Professional Standards of Conduct and Ethics
The smallest published count, but candidates also sign an ethics agreement during application, so this is not a throwaway topic.
- Honest reporting and avoiding misleading statements
- Operating within the boundaries of your certification
Key Takeaway
Do not read the small count for Domain 6 as permission to skip it. A handful of ethics questions can still be the difference between 69 and 70 correct answers, and ethics reasoning questions are often quicker to earn than calculation ones.
Eligibility: Initial and Alternate Routes
Passing the exam is only one piece of becoming certified. The NRSB describes two application paths.
Standard initial route
- An NRSB-approved 16-hour measurement course
- A passing examination result
- A signed application and ethics agreement
- Affiliation with an NRSB-registered business
- Approved devices and the applicable calibration, proficiency, and client-report documentation
A business that uses electrets must also have laboratory accreditation when its RMS reads the devices and generates client reports.
Alternate route
Candidates who hold a current state radon license or an NRPP certificate, plus CE certificates from the current renewal period, may apply through an alternate route in place of the initial course and exam. Be careful with the framing: this is not automatic reciprocity. The other application requirements still apply.
For a fuller breakdown, read RMS Requirements 2026: Eligibility, Prerequisites & How to Qualify. If you are weighing training options, RMS Training is a useful companion.
Fees, Renewal and CE Math
Keep the cost categories separate, because they are billed separately:
| Cost Category | Fact |
|---|---|
| Examination | USD 120, nonrefundable |
| Initial certification or renewal | USD 125 for one year, or USD 200 for two years |
| Other costs | Training, plus any applicable device and business costs, are separate |
For the complete picture, see RMS Certification Cost 2026: Complete Pricing Breakdown.
Renewal requirements
- 8 approved CE credits per year as the standard requirement
- 4 credits per year after at least 10 years of NRSB certification
- Applicable device documentation, as required
- Category II credits cannot exceed 50% of the requirement
What an RMS Is Allowed to Do
The credential's scope centers on four responsibilities:
- Placing and retrieving measurement devices
- Analyzing measurements
- Signing reports
- Overseeing quality assurance, including laboratory and chamber QA
This is a measurement credential. Mitigation work, meaning designing or installing radon reduction systems, falls outside this scope. NRSB's initial-certification webpage contains mitigation wording that conflicts with the RMS exam guide; that wording does not expand what this measurement credential covers. If you are exploring career angles, RMS Jobs and RMS Salary Guide 2026: Complete Earnings Analysis discuss the employment side, and Is the RMS Certification Worth It? Complete ROI Analysis 2026 frames the investment question.
Sequencing Your Review by Domain
You do not need an elaborate system. A domain-driven order that follows the published counts is enough. Here is one way to allocate a four-week review:
Foundations and Field Procedure
- Problem Evaluation, to establish the vocabulary
- Performance of Tests, because placement and conditions feed everything downstream
Analysis of Measurements
- The largest published count deserves the most repetition
- Practice with the calculator and formula sheet exactly as you will use them on exam day
Interpretation, Reporting and Ethics
- Interpretation of Results and Report of Findings together, since reports express interpretations
- Professional Standards of Conduct and Ethics as a short, final pass
Full-Length Practice and Gap Repair
- Timed runs of 100 questions in under two hours
- Revisit whichever domain your misses cluster in
For a broader preparation framework, see RMS Study Guide 2026: How to Pass on Your First Attempt. If you are wondering how demanding the exam is, How Hard Is the RMS Exam? Complete Difficulty Guide 2026 offers perspective, and RMS Pass Rate 2026: What the Data Shows covers what is and is not known about outcomes.
Source Caveats Worth Knowing
A good cheat sheet is honest about what it cannot confirm. Keep these points in mind:
- The six-domain list reflects the study guide's exam subject-area table, not the separate ten-part course-provider syllabus in the same guide. Those curriculum headings are unweighted preparation topics, not an official ten-domain exam structure, and they do not establish exhaustive exam coverage.
- The guide's version number is not a 2026 exam-form release. The study guide carries an April 2026 footer, but that does not prove a separately released 2026 exam form.
- Verify against NRSB directly. Fees and procedures can change, so confirm the exam fee, certification fee, and CE requirements on the NRSB site before you pay or apply.
For a plain-language primer on the credential itself, see What Is RMS? and RMS Certification.
Frequently Asked Questions
The exam has 100 single-best-answer multiple-choice questions with a 2-hour time limit. A score of 70% is required to pass.
No. A personal desktop or laptop is required. Work computers and mobile devices are not permitted, and the Proctor360 system requirements must be met.
You may use one sheet of scrap paper and a pen or pencil, along with the on-screen calculator, formula sheet, and digital notepad. Review the NRSB exam logistics page before test day for any updates.
Failed candidates may register again after 14 days. Each attempt requires its own fee, and the USD 120 exam fee is nonrefundable.
Not by itself. A passing result remains valid for your certification application for one year, but you must also complete the other requirements, including the approved 16-hour course (unless using the alternate route), a signed application and ethics agreement, affiliation with an NRSB-registered business, and the applicable device documentation. Certification fees of USD 125 for one year or USD 200 for two years are separate.