NBME shelf exam percentiles compare your equated percent correct score with a reference group; an EPC of 80 does not mean the 80th percentile. Surgery, psychiatry, neurology and family medicine use their own norms, and your school determines the passing and honors cutoffs (NBME interpretation guide).
1. Know what your shelf score is
NBME clinical science subject exams, the "shelf exams", report an equated percent correct (EPC) score on a 0 to 100 scale. It estimates the percentage of the content you have mastered, statistically adjusted ("equated") so that scores on different forms of the same exam are comparable. It is not your raw percent correct on the questions you saw, and it is not a percentile.
2. Know what the percentile compares you with
NBME builds its norms from first-time takers who sat the exam as an end-of-clerkship test, across a whole academic year. Your percentile is your position within that national group. NBME also publishes quarterly norms, because on some subject exams scores rise for students of the same ability who test later in the academic year. A student who takes the surgery shelf in the first quarter is therefore compared with other first-quarter takers when a school uses quarterly norms.
| Norm type | Who is in it | Why it exists |
|---|---|---|
| Academic-year norms | All first-time end-of-clerkship takers in the year | A single national reference |
| Quarterly norms | First-time takers in one quarter of the year | Scores on some shelves rise later in the year |
3. Find the official norm table
NBME provides the two most recent sets of norms to schools in the score interpretation guide and on MyNBME, its portal for schools, and updates them each year. The public NBME subject exam page carries the guides and sample reports but not the per-subject norm tables. Ask your clerkship coordinator for the table your school uses. Percentile charts posted on prep sites are not NBME's published norms, and they are often several years out of date.
4. Allow for measurement error
NBME gives the total EPC score on a shelf a standard error of the estimate of 4 points. If you re-tested without learning or forgetting, your score would fall within about 4 points two times out of three. Content-area scores on your report are less precise than the total. A small observed difference alone does not establish a reliable difference in proficiency.
5. Know how schools use the score
NBME says subject exam scores should not be used alone to assign grades, but alongside other measures of performance, and that schools should consider how well the exam matches their course objectives. Schools set their own cut-offs, so "the score you need for honors" is a school policy, not an NBME number. Check your clerkship handbook.
6. Use the score report to study
The report shows your EPC by content area against the national comparison group. Since February 2024, NBME has delivered examinee reports through INSIGHTS, its dashboard, a few days after results go to the school. Use the weakest content areas as the first targets for the next rotation and for Step 2 CK, since the same clinical science is tested there.
7. Prepare from day one of the rotation
This part is our advice. Most clerkships are a few weeks long, so a shelf plan has to start on the first day: daily timed questions, same-day review of every miss, and a running list of weak areas that carries into the next shelf. For the NBME self-assessments that mirror shelves, see NBME practice exams. For one-on-one help, see shelf exam tutoring or the page for your rotation, such as the medicine or surgery shelf.
Worked example: reading your shelf score
Say you score 74 on a shelf. With NBME's 4-point standard error of the estimate (NBME), a fair band is 70 to 78. If your school's honors cutoff is 75, an observed 74 is below that cutoff. The uncertainty band describes measurement precision; it does not change the school's grading rule. Your school's norm table then tells you where 74 sits nationally for the quarter you tested in.
| Question | Where the answer comes from |
|---|---|
| What is my score? | Your EPC score on the NBME report |
| How precise is it? | Plus or minus about 4 points (NBME) |
| What percentile is it? | Your school's NBME norm table, academic-year or quarterly |
| Did I get honours? | Your clerkship's own grading policy |
Questions to ask your clerkship coordinator
- Which NBME norm table does the school use: academic-year or quarterly?
- What EPC score corresponds to each grade?
- Is the shelf a set share of the final grade?
- Can I see my content-area report through INSIGHTS?
NBME leaves grading to schools, so these answers come from your clerkship, not from NBME.
One more point from NBME's guide: the norms reflect first-time takers who sat the exam at the end of a clerkship. If you take a shelf as a retake or outside a clerkship, the percentile from the school's table describes the end-of-clerkship group, not students in your situation.
Per-shelf percentile tables: a dated school example
The tables below reproduce selected cutoffs from UTHSC’s 2025–2026 M3 grading document. These are that school’s published conversions and eligibility thresholds, not a universal NBME passing policy or a complete national percentile lookup. Q1–Q4 here correspond to 0–1, 2–3, 4–5 and 6 clerkships completed before the rotation. Use your own school’s current table for your grade.
Surgery shelf percentiles
| UTHSC threshold | Q1 EPC | Q2 EPC | Q3 EPC | Q4 EPC |
|---|---|---|---|---|
| 75th: honors eligibility | 77 | 79 | 79 | 79 |
| 55th: high-pass eligibility | 73 | 74 | 75 | 75 |
| 5th: pass | 57 | 59 | 60 | 60 |
A 76 is below this example’s 75th-percentile honors cutoff in every quarter, but the table does not establish its exact percentile. Do not interpolate an exact national rank from three grade thresholds. See the original school table.
For preparation help on this rotation, see Surgery shelf tutoring.
Psychiatry shelf percentiles
| UTHSC threshold | Q1 EPC | Q2 EPC | Q3 EPC | Q4 EPC |
|---|---|---|---|---|
| 75th: honors eligibility | 88 | 88 | 89 | 89 |
| 55th: high-pass eligibility | 85 | 85 | 86 | 86 |
| 5th: pass | 73 | 74 | 74 | 74 |
The psychiatry example has different numerical thresholds from surgery. An 85 meets the listed high-pass threshold in Q1–Q2 but falls below the Q3–Q4 threshold of 86. That is a school-specific eligibility comparison, not a predicted grade at another school. See the original school table.
For preparation help on this rotation, see Psychiatry shelf tutoring.
Clinical neurology shelf percentiles
| UTHSC threshold | Q1 EPC | Q2 EPC | Q3 EPC | Q4 EPC |
|---|---|---|---|---|
| 75th: honors eligibility | 85 | 85 | 85 | 85 |
| 55th: high-pass eligibility | 81 | 82 | 82 | 82 |
| 5th: pass | 66 | 67 | 67 | 68 |
Here the honors threshold stays at 85 across quarters while the passing threshold changes. Check the row as well as the column; a stable honors number does not mean the entire conversion table is unchanged. See the original school table.
For preparation help on this rotation, see Clinical neurology shelf tutoring.
Family medicine shelf percentiles
| UTHSC threshold | Q1 EPC | Q2 EPC | Q3 EPC | Q4 EPC |
|---|---|---|---|---|
| 75th: honors eligibility | 79 | 80 | 80 | 80 |
| 55th: high-pass eligibility | 75 | 75 | 75 | 75 |
| 5th: pass | 61 | 62 | 62 | 62 |
A family medicine shelf percentile is a relative rank within the applicable shelf reference group. This example connects selected ranks to EPC cutoffs; it does not convert a percentile into a raw percentage of questions correct. See the original school table.
For preparation help on this rotation, see Family medicine shelf tutoring.
Can I use these tables to find the 90th percentile?
No. They give selected 5th, 55th and 75th percentile thresholds in a named school document. A 90th-percentile target requires the correct subject’s fuller norm table and the school’s chosen reference period. Ask your coordinator for that table rather than extrapolate from the honors line. NBME guide to norms.
Our advice: identify the grade requirement before choosing a target. “Honors” may involve more than the shelf, and the shelf cutoff may be an eligibility threshold rather than the whole grade calculation. Put the written policy beside your score report so you can distinguish the observed result, percentile rank and final clerkship grade.
From the shelf report to a weekly study plan
Sean tutors shelf students and builds the work around rotation hours. Sessions use live questions while the student explains the reasoning; the next week’s plan follows the weak areas and repeated decision errors. Shelf tutoring costs $349 per 50-minute session. Explore shelf tutoring or book an introductory consult.
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For the next exam, use Step 2 CK passing and target scores and Step 2 CK percentiles. For other rotations, see pediatrics shelf tutoring and medicine shelf tutoring.