# Step 2 CK Score Predictor (UWSA, NBME and Free 120)

_Data as of 2026-09-29. Interactive predictor at https://www.stepgenie.app/tools/step-2-ck-score-predictor._

## What will I score on Step 2 CK?

NBME reports a CCSSA total on the Step 2 CK scale as an estimate of your performance, but publishes a probability of passing rather than a three-digit forecast. This tool combines your CCSSA and UWSA results, halving each one's weight for every 14 days it is older than your newest, and reports the reading your inputs support.

## How the combined estimate is built

1. Each assessment is converted on its own (NBME forms as-is with NBME's ±8; UWSA 1 minus 6.5 and UWSA 2 minus 4 up to a score of 255, then a deduction rising in a straight line to 12.5 at 270 and staying there, because the sources say the gap widens above 255, to 10-15 points for top scorers; a higher UWSA never converts to a lower estimate). The text on usmlepredictor.com's page puts the gap above 255 at 10-15 points, but the calculator on the same page subtracts at most 7 points from a UWSA 2. This tool follows the text, so for a UWSA 2 of 270 or more it subtracts 12.5 points, where that calculator subtracts 7.
2. Each assessment's weight halves for every 14 days it is older than the newest one entered (this tool's rule, not a published statistic).
3. The range is the weighted mean of the inputs' ranges, never narrower than the exam's 6-point SEM.
4. A CCSSA total and a calibrated UWorld score are different quantities (NBME reports the CCSSA on the Step 2 CK scale, but one form carries ±8 points of measurement error), so the outputs are gated on what you entered: NBME's own probability of passing only for an all-CCSSA set, a percentile from the USMLE norms updated 2026-08-17 only for an all-UWorld set, and for a mixed set the centre and range alone. NBME's table is never extrapolated onto UWorld forms.
5. Free 120 and bare percent-correct entries are shown as readiness bands and left out of the average.

## How much students gained between each NBME form and exam day (step2predictor.com, 2,524 reports)

| NBME form | Mean gain by exam day | n | r | Typical error | Median days before exam |
| --- | --- | --- | --- | --- | --- |
| 9 | +21 | 1276 | 0.68 | 6.8 | 45 |
| 10 | +14 | 1975 | 0.67 | 6.3 | 30 |
| 11 | +12 | 2086 | 0.69 | 6.3 | 25 |
| 12 | +14 | 1902 | 0.68 | 6.2 | 21 |
| 13 | +11 | 1859 | 0.7 | 6.1 | 15 |
| 14 | +8 | 1714 | 0.71 | 5.9 | 10 |
| 15 | +7 | 603 | 0.7 | 5.7 | 8 |
| 16 | +2 | 244 | 0.71 | 5.3 | 6 |

## Step 2 CK by specialty group (NRMP Charting Outcomes 2026, U.S. MD seniors, StepGenie grouping)

Overall matched median 253 (n = 14,889) vs unmatched 244 (n = 1,636).

| Group | Matched median range | Matched Q1 range | Matched Q3 range |
| --- | --- | --- | --- |
| Highly competitive surgical and procedural | 255-261 | 246-256 | 263-266 |
| Moderately competitive | 251-256 | 238-247 | 259-264 |
| Less score-selective | 244-249 | 233-240 | 254-259 |

## Step 2 CK score to percentile (USMLE, updated 2026-08-17)

| Step 2 CK score | Percentile |
| --- | --- |
| 300 | 100 |
| 295 | 100 |
| 290 | 100 |
| 285 | 100 |
| 280 | 100 |
| 275 | 98 |
| 270 | 93 |
| 265 | 83 |
| 260 | 71 |
| 255 | 58 |
| 250 | 44 |
| 245 | 32 |
| 240 | 23 |
| 235 | 15 |
| 230 | 9 |
| 225 | 6 |
| 220 | 3 |
| 215 | 2 |
| 210 | 1 |
| 205 | 0 |
| 200 | 0 |

## Accuracy caveats

Every figure on this page is an official USMLE/NBME figure, a community estimate, or StepGenie's own derivation, and the tool labels which is which. Official: the Step 2 CK percentile norms (updated 2026-08-17), NBME's July 2025 CCSSA pass-probability table on the 218 standard, and NBME's likely score ranges (±8 points for a CCSSA, ±4 EPC points for a CBSSA), which in NBME's words show how much your score could vary if you tested again without learning or forgetting: about two-thirds of the time it would land within that many points. Community: every UWorld, Free 120 and percent-correct conversion, the legacy Step 1 three-digit regressions, and EliteMedicalPrep's second-hand Step 1 probability points (EPC 64 -> 92%, 68 -> 97%). StepGenie's own derivations, labelled "StepGenie estimate": the readiness-band cut-offs, the Free 120 band, and the Step 1 probability interpolated between those points and the EPC 73 -> 99% example on NBME's sample report. The community sources disagree with each other in places, sometimes on direction, and none has been validated against outcomes by an independent party. Two different ±8s circulate: NBME's CCSSA likely score range and USMLE's standard error of the estimate for Step 2 CK (about 8 points). Both describe how far a score would move on retesting without learning or forgetting, about two-thirds of the time; neither is a forecast interval for your exam score. The exam's standard error of measurement is about 6 points. Use the result to decide whether you are ready, not to forecast a number.

## Frequently asked questions

### How does the predictor combine several assessments?

Each assessment is converted on its own: NBME forms count as-is, carrying NBME's ±8 likely score range (a retest band on the score, not a forecast interval for your exam score); UWorld forms are adjusted for the over-prediction usmlepredictor.com and nbmescore.com report near exam day. Each assessment's weight then halves for every 14 days it is older than your newest, so a six-week-old form has an eighth of the say of one from this week. The half-life is this tool's rule, not a published statistic. The range never narrows below the exam's 6-point standard error of measurement. A CCSSA total and a calibrated UWorld score are different quantities, so a pass probability is shown only for an all-CCSSA set and a percentile only for an all-UWorld set.

### Do NBME forms under-predict Step 2 CK?

Relative to what students go on to score, yes. NBME's own July 2025 table puts the 50/50 point at a CCSSA total of 194 against a 218 passing standard: half the examinees at that total clear 218 on the real exam, which could not be true if the CCSSA total were an unbiased forecast of it. Community data agrees near the passing region but shrinks the gap near exam day -- step2predictor.com's 2,524 reports show a mean gain of 21 points over NBME 9, taken a median 45 days out, but only 2 over NBME 16, taken a median 6 days out, so most of that gap is studying rather than miscalibration. This tool adds nothing to your total; it shows the probability NBME publishes and the community gain separately.

### Does UWSA 2 over-predict or under-predict Step 2 CK?

Both claims circulate, and they measure different things. Near exam day, usmlepredictor.com finds the UWSA 2 over-predicts by 3-5 points (nbmescore.com: 0-5). step2predictor.com measures the raw change instead: a mean gain of 6 points by exam day (n = 1,918, r = 0.72), with a median 9 days of studying left. This predictor subtracts the over-prediction, widening it from 255 to 270 so a higher UWSA 2 never converts lower, and shows the gain as context. The text on usmlepredictor.com's page puts the gap above 255 at 10-15 points, but the calculator on the same page subtracts at most 7 points from a UWSA 2. This tool follows the text, so for a UWSA 2 of 270 or more it subtracts 12.5 points, where that calculator subtracts 7.

### What Step 2 CK score do I need for my specialty?

Among U.S. MD seniors in the 2026 Match, the median Step 2 CK score was 253 for applicants who matched to their preferred specialty (n = 14,889) and 244 for those who did not (n = 1,636), per NRMP Charting Outcomes 2026. Grouped by competitiveness, matched medians ran 255-261 in the surgical and procedural specialties, 251-256 in moderately competitive fields and 244-249 in the less score-selective ones. That report covers consenting U.S. MD seniors only, so it says nothing about DO or international graduates.

### Is this predictor on the new 218 passing standard?

Yes. Pass probability comes from NBME's July 2025 CCSSA table, which was recalculated for the 218 minimum that took effect on 2025-07-01, and percentiles come from the USMLE norms updated 2026-08-17 (first-takers from LCME-accredited schools, July 2023 to June 2026, with Canadian schools included through June 2025; 2025-26 mean 251, SD 15). Several third-party predictors still show the April 2026 percentile edition, in which 250 was the 47th percentile rather than the 44th, and nbmescore.com's NBME 14 page still cites the old 214 passing score.

## Sources

- Official: [USMLE Step Examination Score Interpretation Guidelines (updated 17 August 2026)](https://www.usmle.org/sites/default/files/2022-05/USMLE%20Step%20Examination%20Score%20Interpretation%20Guidelines_5_24_22_0.pdf) (as of 2026-08-17)
- Official: [USMLE -- Change to Step 2 CK passing standard begins July 1, 2025](https://www.usmle.org/change-step-2-ck-passing-standard-begins-july-1-2025) (as of 2025-07-01)
- Official: [USMLE Bulletin of Information -- Scoring and score reporting](https://www.usmle.org/bulletin-information/scoring-and-score-reporting) (as of 2026-09-05)
- Official: [USMLE -- Performance data (pass rates by examinee group)](https://www.usmle.org/performance-data) (as of 2026-09-05)
- Official: [NBME -- Updated probabilities of passing Step 2 CK for CCSSA and CCSE (July 2025, 218 standard)](https://www.nbme.org/sites/default/files/2025-07/Updated_Probabilities_for_CCSSA_and_CCSE.pdf) (as of 2025-07-01)
- Official: [NBME -- Gauging readiness for USMLE Step 2: CCSSA/CCSE guidance (March 2025)](https://www.nbme.org/wp-content/uploads/2026/04/CCSSA_CCSE_Guidance.pdf) (as of 2025-03-01)
- Official: [NBME -- Sample CCSSA Examinee Performance Report (December 2024)](https://www.nbme.org/wp-content/uploads/2026/04/Comprehensive_Clinical_Science_Self-Assessment_Sample.pdf) (as of 2024-12-11)
- Official: [NBME -- Common questions about CCSSA 2022 score report changes (for educators)](https://www.nbme.org/sites/default/files/2022-12/For_Educators_Common_Questions_CCSSA_2022_Score_Report_Changes.pdf) (as of 2022-11-01)
- Official: [NBME -- Sample CBSSA Examinee Performance Report (December 2024: EPC 73, 99% probability of passing, model last updated August 20, 2024)](https://www.nbme.org/wp-content/uploads/2026/04/Comprehensive_Basic_Science_Self-Assessment_Sample.pdf) (as of 2024-12-09)
- Community estimate: [Elite Medical Prep -- NBME 25 to NBME 30: best predictor for passing Step 1 (quotes NBME's July 2024 probability update)](https://elitemedicalprep.com/nbme-25-nbme-30-best-predictor-for-passing-step-1/) (as of 2025-09-01)
- Community estimate: [step2predictor.com -- How the model works (2,524 r/Step2 score-release posts, 2023-2026)](https://step2predictor.com/learn.html) (as of 2026-08-01)
- Community estimate: [step2predictor.com -- NBME 9 to 16, UWSA 1/2 and Free 120 conversion pages](https://step2predictor.com/nbme-14-conversion.html) (as of 2026-08-01)
- Community estimate: [usmlepredictor.com -- NBME score predictor (Step 2 CK)](https://usmlepredictor.com/nbme-score-predictor/) (as of 2026-07-01)
- Community estimate: [usmlepredictor.com -- UWSA score predictor (Step 2 CK)](https://usmlepredictor.com/uwsa-score-predictor/) (as of 2026-07-01)
- Community estimate: [nbmescore.com -- UWSA 2 score conversion (Step 2 CK)](https://nbmescore.com/uwsa-2-score-conversion/) (as of 2026-05-01)
- Community estimate: [nbmescore.com -- Free 120 Step 2 CK score conversion](https://nbmescore.com/free-120-step-2-score-conversion/) (as of 2026-05-01)
- Official: [NRMP -- Charting Outcomes: Characteristics of U.S. MD Seniors Who Matched to Their Preferred Specialty, 2026 Main Residency Match](https://www.nrmp.org/wp-content/uploads/2026/07/MD-Senior_Charting-Outcomes_FINAL.pdf) (as of 2026-07-28)

## Related

- [NBME and UWSA score converter](https://www.stepgenie.app/tools/nbme-score-converter)
- [Step 2 CK score percentiles](https://www.stepgenie.app/usmle/step-2-ck-score-percentiles) -- the current USMLE percentile table, the 251 average, the 218 passing score and earlier editions.
- [Free USMLE self-assessment](https://www.stepgenie.app/self-assessment)