Look up a USMLE Step 2 CK percentile in the current 2023–2026 norm table, find a published score anchor for a target rank, or use a separate custom normal model.
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Step 2 Percentile: Official Table and Normal Model
The official lookup uses Table 2 of the USMLE Score Interpretation Guidelines dated 17 August 2026. It compares Step 2 CK scores with 67,824 first-takers from LCME-accredited medical schools tested from July 1, 2023 through June 30, 2026. The reference group excludes Canadian medical schools beginning with the 2025–2026 academic year.
Percentile is the rounded percentage of that group scoring lower, not percent correct or probability of passing. Norm tables are updated annually, so an older edition can give a different rank for the same score. This source was checked October 20, 2026.
How the Official Lookup Works
At a published five-point score anchor, the calculator returns the table’s rounded rank. Between anchors it reports the two surrounding published ranks without interpolating an exact value. Scores of 155 or below use the source’s grouped bottom row. Published 0% and 100% values are rounded boundaries, not guarantees.
| Step 2 CK score | Published percentage scoring lower |
|---|---|
| 230 | 9% |
| 240 | 23% |
| 250 | 44% |
| 255 | 58% |
| 260 | 71% |
| 270 | 93% |
For example, a score of 252 falls between the published ranks for 250 and 255: 44% and 58%. The source does not give its exact rank. In target-rank mode, the calculator finds the first published score anchor at or above your requested rank. For a 90% target, this is 270 with a published rank of 93%; it does not establish an exact minimum required score.
Custom Normal-Distribution Formula
The separate custom mode computes an approximate rank from an assumed mean and standard deviation:
Here S is the score, M is the assumed mean, SD is the positive standard deviation, and Φ is the standard normal cumulative distribution. To estimate a score from a target rank, use S = M + SD × Φ⁻¹(P/100). The default mean of 251 and SD of 15 are the published annual statistics for 2025–2026. A normal curve based on those values is distinct from the three-year empirical norm table.
For a score equal to your assumed mean, the model returns 50%. With S = 266, M = 251 and SD = 15, z = 1 and the modeled rank is about 84.13%. This modeled result should not be described as an exact official percentile.
Using and Interpreting Your Result
- Select the official table or custom normal model.
- Enter a whole reported score, or select target-rank mode and enter a percentage above 0 and below 100.
- For custom mode, enter the mean and standard deviation for the group you intend to model.
- Select Calculate and read the reference group and method beside the result.
USMLE reports a standard error of measurement of about six Step 2 CK points. Small score differences should not be treated as exact differences in ability. A percentile is not a diagnosis of readiness or an admissions prediction, and scores from different USMLE Steps are not directly comparable.
Common Questions
Why did a percentile change?
A revised norm table drops older examinees and includes newer ones. It changes the reference group, not your reported score.
Can I get an exact percentile between two rows?
No. This calculator reports published bounds. Interpolating between rows would add precision the source does not supply.
Can the target mode tell me the exact score I need?
No. It gives the first published anchor meeting the chosen rank. It cannot infer unpublished intermediate ranks or guarantee a future result.
Does a percentile determine whether I passed?
No. Official pass/fail decisions use USMLE’s passing standard. Check the current USMLE scoring information.
