NBME Shelf Exams: 110 Questions, a 0 to 100 Score, and Where the Percentiles Are

Written by Julian. Checked on October 4, 2026.

An NBME clinical science shelf exam is 110 questions in 2 hours and 45 minutes, from the NBME Subject Examination Timing Chart, checked on October 4, 2026, and it is scored as an equated percent correct from 0 to 100. NBME builds national norms for each exam, for the whole academic year and for each quarter, but it sends them to schools through its MyNBME portal and does not post them publicly. So the honest answer to a percentile question is the norm table your clerkship uses. Every number below comes from an NBME or USMLE page, named where it is used.

Which NBME shelf exams exist, and how long each one takes

NBME calls them Subject Exams; students call the clinical ones shelf exams. NBME lists eight clinical science subject exams: Ambulatory Care, Clinical Neurology, Family Medicine Modular, Medicine, Obstetrics and Gynecology, Pediatrics, Psychiatry and Surgery, on its Clinical Science Subject Exams page, checked on October 4, 2026. NBME says educators typically use them to assess third-year medical students at the end of clerkships. Emergency Medicine and Internal Medicine sit in a separate group, the Advanced Clinical Science exams, which the NBME Subject Exam Program Guide places in the fourth year, sub-internships or residency.

Source: NBME, Subject Examination Timing Chart, checked on October 4, 2026. The chart itself is dated July 2021; it is the version the NBME subject exams page links today. A 15 minute tutorial comes before every web exam and is not in these times.

Every clinical row runs at the same pace. Two hours 45 minutes is 9,900 seconds, and 9,900 divided by 110 is 90 seconds a question, which is this article's arithmetic. The Family Medicine and Internal Medicine rows divide out to 90 seconds too.

How a shelf score is reported: equated percent correct, 0 to 100

A shelf score is an equated percent correct, or EPC, score on a 0 to 100 scale. The NBME Score Interpretation Guide that the clinical science page links, a Psychiatry edition dated January 2024 and checked on October 4, 2026, defines it as the percentage of content mastered: the share of items in the whole content domain you would answer correctly at your proficiency level.

It is close to your raw percent correct but not identical. The Subject Exam Program Guide says EPC accounts for how many questions you answered correctly and how difficult they were, adjusted so a slightly harder or easier form does not move your score. A new exam that has not yet been taken by enough examinees for equating reports a plain percent correct instead.

Two more facts change how you read a score:

• The standard error on the Psychiatry guide is 4 points. Retest with nothing learned or forgotten and your total would land within 4 points of your first score two-thirds of the time, so a 3 point gap is inside that band.
• Some questions do not count. An exam may include unscored field-test questions, and NBME occasionally removes an item from scoring, so your feedback report can list fewer questions than you saw.

NBME shelf exam percentiles: what NBME publishes and what it does not

NBME does not post a shelf percentile table on its public site. The national norms go to schools. The Score Interpretation Guide says NBME provides total academic year and quarterly norms, built from first-time takers who took a form as an end-of-clerkship exam, reported on the EPC scale, and that the two most recent sets come with the score reports and on MyNBME, the portal schools use. The Program Guide describes the norm table as a comparison with a nationally representative group from LCME-accredited medical schools at the same stage of training. Both were checked on October 4, 2026.

The quarterly split exists for a reason NBME states plainly: scores in some subject exams are progressively higher for examinees of equivalent ability who test later in the academic year. On this article's reading, the same score can therefore rank lower against fourth quarter norms than against first quarter norms. Ask your clerkship office which norms it reads your score against.

What you see yourself is a comparison with averages, not a percentile: your Examinee Performance Report puts your EPC for each content area next to the comparison group's average and marks you statistically lower, about the same or higher. The NBME sample Psychiatry performance report prints a comparison group mean of 84 and a standard deviation of 6 for recent administrations. It is a sample with placeholder dates, so read it as the shape of the report, not as this year's norm.

Source: NBME Score Interpretation Guide (Psychiatry edition, January 2024) and Subject Exam Program Guide, checked on October 4, 2026.

How schools use shelf scores in clerkship grades

The school decides what a shelf score is worth. NBME offers Grading Guidelines for every clinical science subject exam and for the Emergency Medicine advanced exam, to help clerkship and course directors set passing and honors grades. NBME reviews them with faculty every two to three years, per the Program Guide, and the Psychiatry Score Interpretation Guide says its guidelines were developed by a nationally representative group of clerkship directors, both checked on October 4, 2026.

NBME also limits their weight. Its guide says subject exam scores should not be used alone but together with other indicators of performance when grades are set, because course objectives vary across schools. The honors cutoff on a given clerkship is your school's number, written in its own grading policy; NBME does not publish one.

A shelf score does not count toward a license. The Program Guide states that subject exam scores cannot be used by examinees for credit toward the exam requirements for medical licensure in the United States.

When and how shelf exams are given, and when scores come back

Your school orders and runs the exam. The Subject Exam Program Guide, checked on October 4, 2026, describes three ways to sit it:

• Web-based at the school, in a secure proctored room with a locked-down browser. The school can order up to the second calendar day before the test date.
• At a Prometric test center, for every clinical science exam except Ambulatory Care. The school sets a testing window of 7 to 14 calendar days and orders at least 28 days before it starts; NBME then emails each student a scheduling permit in about 2 to 3 business days.
• Remotely, which NBME offers for all clinical science and advanced clinical science exams.

For a web exam at the school, results are often posted the calendar day after the testing window ends or the day after that, and posting may take up to three business days. The Score Interpretation Guide says students get an email to view their reports in INSIGHTS 3 to 4 calendar days after results are delivered to the school.

Source: NBME, Subject Exam Fees, checked on October 4, 2026. NBME notes that fees are subject to change.

A score you think is wrong can be rechecked, but only through the school. The school's chief proctor or a course or clerkship director files the request within six months of the test date, NBME charges USD 25 and does not accept payment from examinees, and the answer comes in about two weeks, per the Program Guide.

Shelf exams versus Step 2 CK

Shelf exams and USMLE Step 2 CK come from the same item-writing standard but serve different purposes. The Program Guide says subject exam items are written and reviewed with the same rigor used to create USMLE Step 1 and Step 2 items. Step 2 CK is a licensing exam with a published passing score; a shelf is a school's final exam with none.

Source: NBME Subject Exam Program Guide and Timing Chart; USMLE, Step 2 CK and Examination Results and Scoring; all checked on October 4, 2026.

NBME's bridge between the two is the Comprehensive Clinical Science exam, 200 questions in 5 hours 15 minutes, which NBME says gauges readiness for the USMLE on its subject exams page for examinees. Blueprint weights for Step 2 CK are on the Step 2 CK page, and its percentile table is in the post on Step 2 CK percentiles and the passing score.

A shelf study plan from your own clerkship notes

NBME sells one practice tool built for the shelf: the Clinical Science Mastery Series, self-assessments of 50 questions per form in Clinical Neurology, Emergency Medicine, Family Medicine, Medicine, Obstetrics and Gynecology, Pediatrics, Psychiatry and Surgery. Each costs USD 21, runs 1 hour 15 minutes standard paced or 5 hours self paced, and comes with a conversion table that turns the result into an approximate score on the subject exam scale, from the Clinical Science Mastery Series page, checked on October 4, 2026. MyNBME gives you one year to complete it.

Between those, practice from what the rotation taught you. Upload your clerkship notes, teaching slides or an assigned chapter, ask this site for 20 single best answer questions, and set a 30 minute timer, the shelf pace of 90 seconds a question. Each question prints the sentence it was written from and the page it sits on, checked against the stored page text, so a miss sends you to a page instead of a guess. This is not an NBME product and has no connection to NBME. The sample exam needs no upload or account, and pricing lists the free monthly allowance and the paid options. The page for medical students describes the same routine.

Questions people ask

What is a good NBME shelf exam score?

NBME does not set one. A shelf is scored as an equated percent correct from 0 to 100, and each school sets its own passing and honors cutoffs, often with the Grading Guidelines NBME gives clerkship directors, per the NBME Subject Exam Program Guide, checked on October 4, 2026. Read your score against the norm table your school uses, for the quarter you tested in.

Are NBME shelf exam percentiles published?

Not publicly. NBME gives schools academic year and quarterly norm tables on the 0 to 100 equated percent correct scale, built from first-time takers at the end of a clerkship, through its MyNBME portal, per the clinical science Score Interpretation Guide, checked on October 4, 2026. A shelf percentile chart on a prep site is not an NBME document.

How many questions are on an NBME shelf exam?

110 questions in 2 hours 45 minutes for Medicine, Surgery, Pediatrics, Obstetrics and Gynecology, Psychiatry, Clinical Neurology and Ambulatory Care, from the NBME Subject Examination Timing Chart, checked on October 4, 2026. Family Medicine Modular runs 90, 100 or 110 questions depending on the modules, and a 15 minute tutorial comes before every web exam.

When do NBME shelf scores come out?

Schools often see results the calendar day after the testing window ends or the day after that, and posting can take up to three business days, per the NBME Subject Exam Program Guide, checked on October 4, 2026. NBME's score guide (Psychiatry edition, January 2024) says students are emailed 3 to 4 calendar days after the school receives results, to view them in INSIGHTS.

How much does an NBME shelf exam cost?

For July 1, 2026 to June 30, 2027, NBME lists a clinical science subject exam at USD 52 per examinee at the school, USD 54 remote and USD 106 at a Prometric test center, on its subject exam fees page, checked on October 4, 2026. NBME notes that fees are subject to change.

Do shelf exam scores count toward USMLE or licensure?

No. The NBME Subject Exam Program Guide, checked on October 4, 2026, states that subject exam scores cannot be used by examinees for credit toward the exam requirements for medical licensure in the United States. Step 2 CK is a separate exam, with a passing score of 218 for exams taken on or after July 1, 2025, per USMLE.

Does NBME make a practice shelf exam?

Yes, the Clinical Science Mastery Series: self-assessments of 50 questions per form in eight clinical areas, USD 21 each, 1 hour 15 minutes standard paced, with a table converting the result to an approximate subject exam score. Those details are on the NBME Clinical Science Mastery Series page, checked on October 4, 2026.

Published October 4, 2026.