# NBME Score Converter for Step 1 and Step 2 CK

_Data as of 2026-09-05. Interactive calculator at https://www.stepgenie.app/tools/nbme-score-converter._

## What does my NBME score convert to?

For Step 2 CK, an NBME CCSSA total is already on the exam's three-digit scale, and NBME publishes a pass-probability table for the 218 standard: read that probability rather than treating the total as your predicted score. For Step 1, a CBSSA reports an equated percent correct; NBME's published anchors put EPC 64 at 92% and EPC 68 at 97%.

## How the converter reads each input

- **NBME CCSSA (Step 2 CK, forms 9-16):** the tool reports the CCSSA total with NBME's ±8-point likely score range, which is retest reliability -- how far the same form would move if you sat it again without learning or forgetting -- not the spread around your real score. The headline reading is NBME's own probability of passing, from its July 2025 table on the 218 standard. No percentile is shown: NBME's table puts the 50/50 point at a CCSSA of 194, so a CCSSA total is not a Step 2 CK score and cannot be looked up in the Step 2 CK norms.
- **UWorld UWSA 1 / UWSA 2 (Step 2 CK):** community calibration only, and the one input that does yield a predicted exam score (so it carries a percentile, but no NBME pass probability -- that table's input is a CCSSA total, not a predicted score). usmlepredictor.com finds UWSA 1 runs 5-8 points high and UWSA 2 3-5 points high near exam day (10-15 above 255); the tool subtracts the midpoint and shows a ±7/±6 typical error.
- **Free 120 (Step 2 CK):** no credible three-digit formula exists; the tool returns a readiness band derived from USMLE's "approximately 60% of items" statement plus the 5-10-point easier difficulty nbmescore.com reports.
- **NBME CBSSA (Step 1, forms 25-33):** pass probability interpolated between NBME's published anchors (EPC 64 -> 92%, EPC 68 -> 97%, EPC 69 -> 97%, EPC 73 -> 99%). NBME publishes no numeric bounds for its low-pass range; EliteMedicalPrep reads it as EPC 62-68, and the tool attributes it that way. A legacy three-digit estimate from nbmescore.com's per-form regression is shown for forms 25-31 only.
- **UWSA 1 / UWSA 2 / Free 120 (Step 1):** consensus percent-correct band plus nbmescore.com's legacy-scale regression, labelled as such.

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

Norm group: first-takers from LCME-accredited US medical schools, July 1 2023 - June 30 2026 (N = 67,824). Mean 251, SD 15, SEM 6.

| 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 |

## NBME CCSSA total score to probability of passing Step 2 CK (NBME, July 2025, 218 standard)

| CCSSA total score | Probability of passing Step 2 CK |
| --- | --- |
| 161 and below | 1% |
| 170 | 10% |
| 180 | 23% |
| 190 | 41% |
| 194 | 50% |
| 200 | 64% |
| 205 | 74% |
| 210 | 82% |
| 214 | 87% |
| 218 | 91% |
| 220 | 92% |
| 225 | 95% |
| 230 | 97% |
| 235 | 98% |
| 239 and above | 99% |

## Step 1 readiness bands

| Percent correct (recent CBSSA EPC or Free 120) | Reading |
| --- | --- |
| 70% and above | Likely ready |
| 64-69% | Likely pass |
| 60-63% | Borderline |
| 56-59% | At risk |
| Below 56% | High risk |

## Accuracy caveats

Every figure on this page is either an official USMLE/NBME table or a community estimate, 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 stated likely score ranges (±8 points for a CCSSA, ±4 EPC points for a CBSSA) -- which measure how far the same form would move if you sat it again without learning or forgetting, not how close your real score will land. Community: every UWorld, Free 120 and percent-correct conversion, and the legacy Step 1 three-digit regressions. The community sources disagree with each other in places, sometimes on direction, and none has been validated against outcomes by an independent party. No source cited here supports a ±8-point confidence band around your actual Step 2 CK score: the exam's own standard error of measurement is 6 points, and the best-documented community model puts only 83.7% of students within 8 points of its prediction. Use the result to decide whether you are ready, not to forecast a number.

## Frequently asked questions

### Which NBME form predicts Step 2 CK best?

The newest forms. In step2predictor.com's 2,524-report dataset, NBME 14 and 16 correlate r = 0.71 with the real score and miss by a typical 5.3-5.9 points, against 6.8 points for NBME 9. usmlepredictor.com claims r = 0.92 for form 14 but does not disclose its method. NBME itself publishes no accuracy figure for predicting a real score from a CCSSA; the form you take closest to exam day will be the most accurate simply because less studying happens after it.

### How far off are NBME score predictions?

Further off than the ±8 figure students usually quote. That ±8 is NBME's likely score range, and NBME defines it as retest reliability: how far the same CCSSA would move if you sat it again without learning or forgetting. It says nothing about the gap to your real score. For that, the best-documented community model (step2predictor.com, 2,524 reports) has a mean absolute error of 4.8 points and puts 83.7% of students within 8 points -- so roughly one student in six misses by more. The exam's own standard error of measurement is 6 points, the floor for any predictor.

### When should I take the Free 120?

In the final one to two weeks, after your last NBME form. Students in step2predictor.com's data took the current (2023) Free 120 a median 3 days before Step 2 CK; its 1,718 results correlate r = 0.68 with the real score. It is the only free NBME-written practice on the actual exam interface, which is its main value. It runs 5-10 percentage points easier than a CCSSA form according to nbmescore.com, so read it as a readiness check rather than converting it to a three-digit score.

### What is a passing score on Step 1 and Step 2 CK?

Step 2 CK: 218, effective 2025-07-01 (up from 214). Step 1: 196 on a scale that is no longer reported, since 2022-01-26 you receive only Pass or Fail. USMLE says examinees typically need approximately 60% of items correct, though the exact share varies by Step and form. First-taker pass rates for US MD students were 93% on Step 1 in 2025 and 98% on Step 2 CK in 2024-25 (usmle.org performance data).

### How often do NBME forms and the conversion tables update?

USMLE republishes the percentile norms each August; the current edition is dated 2026-08-17 and covers 67,824 first-takers. NBME recalibrates its pass-probability models about once a year: the CCSSA table was reissued in July 2025 for the 218 standard, and CBSSA reports cite a model last updated 2024-08-20. Passing standards themselves are reviewed every three to four years, so the next Step 2 CK review is due around 2028-2029. Form rosters change too: the community lists CBSSA 32-33 and CCSSA 14-16 as the newest, but nbme.org does not number them, so check MyNBME before buying.

## 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 -- Examination results and scoring](https://www.usmle.org/scores-transcripts/examination-results-and-scoring) (as of 2026-09-05)
- 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 -- Change to Step 1 passing standard begins January 26, 2022](https://www.usmle.org/change-step-1-passing-standard-begins-january-26-2022) (as of 2022-01-26)
- Official: [USMLE -- Step 1 transition to pass/fail only score reporting](https://www.usmle.org/usmle-step-1-transition-passfail-only-score-reporting) (as of 2022-01-26)
- 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 -- 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 -- CBSSA/CBSE score interpretation guidance](https://www.nbme.org/wp-content/uploads/2026/04/CBSSA_CBSE_Guidance.pdf) (as of 2026-04-01)
- Official: [NBME -- Comprehensive Basic Science Self-Assessment](https://www.nbme.org/examinees/self-assessments/comprehensive-basic-science-self-assessment/) (as of 2026-06-01)
- 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: [usmlepredictor.com -- Step 1 accuracy insights](https://usmlepredictor.com/step-1-accuracy-insights/) (as of 2026-07-01)
- 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: [TheMatchGuy -- NBME Step 1 guide to self-assessment exams](https://thematchguy.com/nbme-step-1-guide-self-assessment-exams/) (as of 2026-06-01)
- Community estimate: [Yousmle -- NBME score conversion](https://www.yousmle.com/nbme-score-conversion/) (as of 2023-02-05)
- Community estimate: [predictmystepscore.com -- What is a safe percentage to pass on NBMEs?](https://predictmystepscore.com/blog/digital/what-is-a-safe-percentage-to-pass-on-nbmes/) (as of 2024-01-01)
- Community estimate: [nbmescore.com -- NBME score converter for Step 1 (forms 25-31 regressions)](https://nbmescore.com/nbme-score-converter-step-1/) (as of 2026-05-01)
- Community estimate: [nbmescore.com -- UWSA 1 score conversion calculator (Step 1)](https://nbmescore.com/uwsa-1-score-conversion-calculator/) (as of 2026-05-01)
- Community estimate: [nbmescore.com -- UWSA 2 score predictor for Step 1](https://nbmescore.com/uwsa-2-score-predictor-for-step-1/) (as of 2026-05-01)
- Community estimate: [nbmescore.com -- Free 120 Step 1 score calculator](https://nbmescore.com/free-120-step-1-score-calculator/) (as of 2026-05-01)
- 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)
- 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)

## Related

- [Step 2 CK score predictor](https://www.stepgenie.app/tools/step-2-ck-score-predictor)
- [Free USMLE self-assessment](https://www.stepgenie.app/self-assessment)