Are Shelf Exams Curved? Shelf Exam Scoring and What to Expect

If you are a medical student deep in your clinical rotations, there’s a good chance you have heard whispers (or outright panic) about Shelf Exams. Often, these exams can be the make or break between obtaining Honors or High Pass – a big deal for students applying into highly competitive specialties or for anyone who wants to achieve the best marks they possibly can! Some students claim they are “curved like crazy”, while others insist there is no curve at all. Many simply wonder: How does this scoring system even work?

The truth is: Shelf Exams are not graded in the same way as a college course exam – and understanding how they are scored (and what a “curve” means in this context), and how this fits into your overall grade, can help you study smarter and worry less.

In this guide, we’ll cover:

• What Shelf Exams are and why they matter
• The difference between NBME Shelf Exams and other clinical assessments
• How Shelf Exam scoring works
• Whether Shelf Exams are “curved” and what that means for your grade
• Passing scores for Shelf Exams
• How much Shelf Exams matter for your transcript and residency
• How Shelf Exams compare to Step 2 CK
• Strategies to prepare effectively (and how tutoring can help)

What Are Shelf Exams?

Let’s start with the basics. Shelf Exams – officially called NBME Clinical Science Subject Exams – are standardized tests created by the National Board of Medical Examiners (NBME). Each core clinical rotation in medical school (Internal Medicine, Surgery, Pediatrics, Psychiatry, Family Medicine, and Obstetrics/Gynecology) often ends with one of these exams. Importantly, not all schools necessarily use an exam that comes directly from the NBME. Some institutions will create their own shelf exams; however, in our experience, MOST schools obtain them directly from the NBME. Regardless, the major cumulative examination at the end of each clerkship is traditionally called the shelf exam, irrespective of who has created it.

Purpose:

• To assess your ability to apply medical knowledge in a clinical context
• To standardize grading across different clerkship sites and teaching hospitals (when taking exams made by the NBME)
• To help schools gauge your preparedness for Step 2 CK

Unlike most in-house medical school exams, Shelf Exams from the NBME are written and maintained by the same organization that creates the USMLE exams. That means the question style, content depth, and clinical reasoning expectations closely mirror what you’ll encounter on Step 2 CK. And, importantly, it helps compare students from different medical schools where in-house examinations can vary wildly.

How Shelf Exam Scoring Works

The exact manner in how you are provided your shelf exam score varies significantly across schools. Some schools will not provide you a detailed score report, others will inundate you with data. It is important to think about how scoring works and is reported at your specific institution. Below, we provide a general framework:

1. Raw Score

When you take a Shelf Exam, the NBME records the number of questions you answer correctly. This is your raw score – but it is not what you will always see reported.

2. Scaled Score

Because each form of a Shelf Exam can have slightly different difficulty levels, the NBME converts your raw score into a scaled score using statistical equating. This process ensures that a 75 on one version of the exam is equivalent in meaning to a 75 on another. This is, in a way, curving the examination. HOWEVER, it is important to recognize that the NBME is doing this to ensure that scores ACROSS examinations are of similar difficulty, they are not necessarily changing scores WITHIN an exam.

Imagine we took a single group of students and have them take two different shelf exams, one easy and one hard. The harder test would likely lead to lower raw scores than the easier test. However, given that the students taking the test are the SAME people, their knowledge has not changed in between taking the two tests; rather, one was just harder than the other. So, scaling your score allows the NBME to factor in the difficulty of one test relative to another and provide scores that best reflect the students knowledge.

For most Shelf Exams:

• Scaled scores are reported with a mean around 70–75 (on an NBME-specific scale), with a standard deviation of roughly 8–9.
• Scores are also compared to a national percentile – showing how you did compared to other examinees nationwide.

3. Percentile Rank 

NBME percentiles are based on a reference group of medical students who have taken the exam in recent years. If you’re in the 60th percentile, you scored higher than 60% of this national reference group.

 4. How Your School Uses the Score

This is where it gets tricky – NBME provides a scaled score, but your medical school decides how to interpret it and factor it into your overall grade.

Some schools:

• Combine Shelf Exam scores with clinical evaluations
• Require a minimum Shelf score to pass the clerkship
• Assign letter grades based directly on the percentile (e.g., ≥ 80th percentile = Honors) – less common as this does not factor in clinical evaluations.

In our experience, most schools will incorporate the shelf exam score into your overall clerkship grade. For example, your clerkship grade could be 60% based on clinical evaluations and 40% based on your shelf score, and you are required to obtain an 80% or greater grade overall to obtain honors. Other schools will have a similar schema, but also state that you need to obtain a minimum shelf score to be eligible for honors (so, not only do you need an 80% overall, you need to also score a 70% or greater on the shelf exam – this makes it so students who fail the shelf exam are not eligible for honors).

Are Shelf Exams Curved?

This is the million-dollar question. The short answer:

Shelf Exams are not “curved” in the traditional sense of grading within your specific class. Instead, they are statistically scaled to account for small differences in difficulty between different test forms.

Some schools will also scale their exams based on when during the year they are taken – they do this because students, for example, who take their internal medicine shelf early in the year will often know less than those who take it at the end of the year. This is because things you learn on one shelf exam, will help you with another shelf exam. So it is challenging to directly compare these two groups of test takers, which is where scaling comes in.

Altogether, this means that:

• If your classmates all score poorly, your score does not necessarily go up (just because you all did bad does not mean your school will fix this)
• Your score reflects your performance compared to a national reference group, not just your classmates.
• Your score may be adjusted based on when in your clinical year the exam is taken (very school dependent)

Why the confusion?

Students often feel like Shelf scores are “curved” because:

• Schools might assign grades relative to class performance (this is an internal curve – not from the NBME).
• NBME scaling can make the relationship between raw questions correct and scaled scores feel non-linear (which if often is!)
• National percentile ranks inherently compare you to others, which feels like a curve.

In this sense, we can clarify two terms:

• Curved = scores are adjusted so the average score on the test is set at some arbitrary number (for example, if the raw average was a 50%, the instructor can “curve” the data so the average is a 50% – in this scenario, everyone’s score increases)
• Scaled = scores are adjusted relative to the difficulty of the examination (for example, if you took a test that was deemed significantly more challenging than a different test that other people took, your score may be scaled up or down or not at all).

So, if you are asking yourself How Much Are Shelf Exams “Curved”?

If by “curve” you mean adjusted upward to help the class average, the short answer is: they usually aren’t.

If by “curve” you mean your score is converted to account for differences between test forms – you are likely talking about “scale”, then yes – there is some statistical adjustment. But this adjustment is designed for fairness, not to inflate scores.

Example:

Let’s say Form A of the Pediatrics Shelf turns out to be slightly harder than Form B. If you took Form A and got 70% correct, while someone on Form B also got 70%, the NBME’s equating process might scale your score up slightly to reflect that your form was more difficult.

NBME Shelf Exam Passing Scores

There is no single universal “passing score” for Shelf Exams. The NBME itself does not set a pass/fail threshold – it simply reports your scaled score and percentile. Ultimately, your medical school determines the passing standard and how these factors into your grade.

Common patterns:

• Many schools set a passing score around 5th–10th national percentile (often a scaled score of about 60–65).
• Many schools will use a fixed scaled score (e.g., ≥ 60) regardless of percentile.
• A few schools have higher passing thresholds for certain rotations.

Make sure to check your school’s clerkship syllabus. Passing cutoffs can vary by rotation and even by academic year, in addition to how much weight the shelf exam carries into your overall clerkship grade.

Do Residencies Look at Shelf Exam Scores?

 Generally, no – at least not directly.

Shelf Exam scores are NOT reported on your ERAS transcript, and the NBME does not share your scores with residency programs. However – there are ways for programs to learn about your shelf exam scores directly and indirectly:

• Clerkship grades are often reported on your transcript and MSPE (Dean’s Letter).
• If your school heavily weights Shelf scores in determining your overall clerkship grade (Honors or High Pass), then strong Shelf performance will boost your residency application.
• Shelf exams tend to be the deciding factor between honors vs. high pass vs. pass if most students at a certain program receive excellent clinical marks.
• Poor Shelf performance can impact your Step 2 CK prep, which programs do see and utilize heavily in deciding interviews and ranking

In short: Residency directors won’t see “72% on Surgery Shelf” in your file, but they might see “Pass” instead of “Honors” for Surgery—which could possibly because of that specific Shelf score.

Are Shelf Exams Harder Than Step 1?

This is entirely subjective. In our experience, they are generally not more challenging for two major reasons. First, the tested material is more relevant to your everyday practice of medicine, so the sheer utility of the questions is more interesting and meaningful to students. Second, the tested material does not primarily revolve around the basic sciences, which are usually more challenging for students as compared to clinical science. However, they can feel harder, but for different reasons:

• Shelf Exams are rotation-specific, so you have less time to prepare for each compared to the weeks to months you may have spent on Step 1.
• You often take Shelf Exams while balancing clinical duties, which cuts into study time.
• Shelf question stems can be longer, with more complex distractors.

How to Interpret Your Shelf Exam Score Report 

After your exam, you’ll receive a score report that typically includes:

• Your scaled score
• A national percentile
• A score breakdown by content area (e.g., cardiology, gastroenterology for Internal Medicine)

General points:

• How the scaled score equates to a percentile is highly variable depending on the rotation and academic year.
• National averages will shift slightly over time.
• Weaknesses in specific content areas can guide your studying for Step 2 CK.

Strategies to Succeed on Shelf Exams

Since Shelf Exams are not curved in the way many students expect, your best bet is to prepare as if you are aiming for the highest absolute score you can get (sounds simple but it is the truth!).

1. Study Consistently Throughout the Rotation

Don’t wait until the final week to open UWorld/Amboss. Doing 10–20 questions per day during the rotation will build both content knowledge and clinical reasoning. Your weekends are a time to catch up on life, but if you want to get honors, you will need to study during this time too!

2. Use the Right Resources

For most students, a high-yield combo looks like:

• UWorld/Amboss Step 2 CK Question Bank (rotation-specific sections)
• NBME practice shelf exams
• A trusted review book or video series (e.g., Case Files, Blueprints, Step Up)

3. Focus on Weak Areas Early

If your mid-rotation practice exam shows you are weak in OB emergencies or pediatric infectious diseases, don’t procrastinate fixing those gaps. Fail early and learn quickly from your mistakes.

4. Simulate Exam Conditions

Take at least one full-length NBME practice exam before test day to build stamina and pacing skills. We often recommend students take as many practice shelf exams as they can prior to test day.

5. Get Expert Help When Needed

If you are struggling with Shelf Exams, do not wait until Step 2 CK to figure out how to master these types of questions. The questions on the shelf exams are nearly identical what you will encounter on Step 2 CK. A tutor can:

• Help you understand why you are missing questions
• Build a study schedule around your clerkship duties
• Provide targeted teaching in your weakest topics
• Develop your test taking skills

Elite Medical Prep offers personalized tutoring from top scorers who’ve been exactly where you are!

Final Takeaways: Shelf Exam Curving & Scoring

• NBME Shelf Exams are not curved within your class – scores are scaled to adjust for exam difficulty and compared to a national reference group.
• Passing scores vary by school – know your institution’s policy.
• Shelf scores matter indirectly for residency through clerkship grades, Dean’s Letters, and Step 2 CK prep.
• They can feel harder than Step 1 due to time pressure and concurrent clinical duties.
• Consistent study and targeted prep are the most reliable ways to improve scores – no curve will save you if you’re unprepared!

Bottom line: Don’t rely on a rumored “curve” to rescue your grade. Understand how your Shelf Exams are scored, prepare systematically, and seek help early if needed. With the right approach, you can turn these Shelf Exams into a stepping stone for Step 2 CK success – and ultimately, residency!

If you want a personalized study plan and expert guidance to help you excel on Shelf Exams and beyond, check out Elite Medical Prep – our tutors are physicians and top-scoring students who know how to turn a good score into a great one!