How Predictive Is NBME 28 for Step 1?

NBME 28 has been submitted to Predict My Step Score 39,386 times and tracked against the real Step 1 results students went on to report. In that data, NBME 28 was a useful pass signal — clearly ahead of a coin flip.

What is NBME 28?

The NBME Comprehensive Basic Science Self-Assessments (CBSSA) — the numbered "NBME forms" — are written by the National Board of Medical Examiners, the organisation that writes Step 1 itself. Since Step 1 became pass/fail, each form reports an equated percent correct and an estimated probability of passing Step 1 if you tested within about a week, rather than a 3-digit score. That is why the numbers on this page are on a percent scale, and why we report how well each form separated passes from fails rather than a score conversion.

What is a good NBME 28 score?

In our data, NBME 28 scores ranged from 17% to 99%. Since Step 1 is pass/fail, there is no target number to hit: a "good" NBME 28 score is one that sits comfortably inside the range where passing was the norm for students in our data, with enough margin that one rough block on the day would not put you at risk.

When should you take NBME 28?

NBME forms work best as spaced checkpoints through dedicated study, roughly one every one to two weeks, saving the newest forms for the final stretch since they match the current exam most closely.

Does it matter when you take NBME 28?

Timing matters twice over. First, a score from six weeks out is a snapshot of a student who then kept studying, so early tests tend to sit below the real result — much of what looks like "underprediction" is simply improvement after the test. Second, our predictor does not treat every score you enter equally: each one is weighted by the exam's R² and by how recently you took it, with a recency factor that decays exponentially from your most recent test back to your oldest, and your three most recent scores drive the final adjustment. Enter the days-before-exam for each test honestly — it changes the answer.

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NBME 28 score

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Takes you to the predictor with NBME 28 already filled in — add your other practice exams there for the full prediction.

How NBME 28 compares

Wondering whether to take NBME 28 next? See which practice tests are most predictive.

NBME 28 vs the other NBME forms

NBME 28 is one of 9 NBME forms in our Step 1 data, and they are not interchangeable: predictive power differs from form to form. The others — NBME 25, NBME 26, NBME 27, NBME 29, NBME 30, NBME 31, NBME 32, NBME 33 — each have their own page, and the full side-by-side ranking is available to premium users. How predictive is NBME 25? · How predictive is NBME 26? · How predictive is NBME 27? · How predictive is NBME 29? · How predictive is NBME 30? · How predictive is NBME 31? · How predictive is NBME 32? · How predictive is NBME 33?

Frequently asked

Is NBME 28 accurate?

In our data NBME 28 was a useful pass signal — clearly ahead of a coin flip. No single practice test settles pass/fail on its own, though — combining your scores, weighted by each exam's track record and timing, gives a much better read than any one sitting. Predict your Step 1 score →

Does NBME 28 overpredict or underpredict Step 1?

Step 1 is pass/fail, so there is no point bias to report. In our data NBME 28 was a useful pass signal — clearly ahead of a coin flip.

Is NBME 28 or UWSA 1 more predictive?

UWSA 1 is more predictive in our data. The exact gap is part of the full ranking, which is available to premium users.

Where does this data come from?

39,386 NBME 28 scores have been submitted to Predict My Step Score so far. Whenever a student also reports their actual Step 1 result, the pair goes into the model behind this page; it was last refit on 2026-05-14.

Can't I just ask ChatGPT how predictive NBME 28 is?

Not reliably. A prediction is only as good as the paired data behind it: real NBME 28 scores matched to the real Step 1 result those same students went on to get. General-purpose AI models are trained on forum posts and articles, not on verified outcomes, so what you get back is a summary of anecdotes rather than a calibrated estimate. The numbers on this page come from students who reported both. Read more →

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Data refreshed 2026-05-14.

All Step 1 practice exams · NBME 25 · NBME 26 · NBME 27 · NBME 29 · NBME 30 · NBME 31 · NBME 32 · NBME 33 · Have an offline test? Convert it to a score →