# NBME and UWSA Score Converter for Step 1 and Step 2 CK

_Data as of 2026-09-29. Interactive calculator at https://www.stepgenie.app/tools/nbme-score-converter._

## What does my NBME score convert to?

For Step 2 CK, a CCSSA total is on the exam's three-digit scale, and NBME publishes pass probabilities for the 218 standard: read the probability. For Step 1, a CBSSA reports an equated percent correct and NBME's probability of passing. NBME publishes no curve; EliteMedicalPrep reports NBME's July 2024 update put EPC 64 at 92% and 68 at 97%.

## How the converter reads each input

- **NBME CCSSA (Step 2 CK, forms 9-16; NBME currently sells seven, so one of these is no longer on sale):** NBME reports the total on the same 1-300 scale as Step 2 CK, and the tool shows it with NBME's ±8-point likely score range: if you tested again without learning or forgetting, your CCSSA score would land within 8 points of this one about two-thirds of the time. That measures the imprecision of this score, not how much you will learn before exam day, so it is not a forecast interval for your Step 2 CK score. The headline reading is NBME's probability of passing: if your report's probability model is dated after October 15, 2024, use the figure printed on your report; otherwise use NBME's July 2025 table for the 218 standard, below. No percentile is shown: one form carries ±8 points of measurement error and scores move before exam day, so a percentile would overstate precision. NBME's table puts its 50/50 point at a CCSSA of 194, 24 points below 218, because a low score on one form is partly measurement error and most examinees score well above the standard.
- **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 (nbmescore.com: 0-5 for UWSA 2), and says the gap widens above 255 for both forms, to 10-15 points for top scorers, as nbmescore.com does for UWSA 2. The tool subtracts the midpoint of the near-exam-day band (6.5 for UWSA 1, 4 for UWSA 2) up to 255. Switching to the top-scorer band at 255 would make a 256 convert lower than a 255, so above 255 the deduction instead rises in a straight line to 12.5, the midpoint of 10-15, at 270 and stays there; usmlepredictor.com describes its own adjustment above 255 as progressive. 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. The tool shows a ±7/±6 typical error, within the ranges those calculators claim, which is meant as a miss against real results but rests on the calculators' own unpublished data. step2predictor.com's figures point the other way (+17 and +6 by exam day): studying in between explains much of the UWSA 1 gap, but UWSA 2 is usually taken about 9 days out, so for UWSA 2 the sources genuinely conflict and the direction of the correction is uncertain.
- **Free 120 (Step 2 CK):** no credible three-digit formula exists; the tool returns a readiness band that is StepGenie's own derivation from USMLE's "approximately 60% of items" statement (raw percent on the real exam) plus the 5-10-point easier difficulty nbmescore.com reports. The two figures rest on different footings, so read the band as a direction.
- **NBME CBSSA (Step 1, forms 25-33; NBME currently sells seven, so two of these, 25 among them, are no longer on sale):** NBME prints a probability of passing on every CBSSA report but publishes no table or curve. The tool interpolates between second-hand points: EliteMedicalPrep reports that NBME's July 2024 update put EPC 64 at 92% and EPC 68 at 97%, and NBME's December 2024 sample CBSSA report shows EPC 73 at 99% (model last updated 2024-08-20; NBME updates it annually). The interpolated figure is a StepGenie estimate; the probability printed on your own report is NBME's. NBME's ±4 EPC likely score range describes retest variability (within 4 points about two-thirds of the time, without learning or forgetting), not the accuracy of a Step 1 prediction. NBME publishes no numeric bounds for its low-pass range; EliteMedicalPrep reads it as EPC 62-68 and the University of Arizona as 61-70, and the tool attributes them that way. A legacy three-digit estimate from nbmescore.com's per-form regression is shown for forms 25-31 only, against 196, the passing standard on the three-digit scale USMLE no longer reports.
- **UWSA 1 / UWSA 2 / Free 120 (Step 1):** StepGenie's readiness band (set on CBSSA equated percent correct, so rougher on a raw percent) plus nbmescore.com's legacy-scale regression, labelled as such.

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

NBME issued this table for reports whose probability model is dated October 15, 2024; if your report's model is dated after that, use the probability printed on your report. The table assumes you test within one week of the form, and NBME warns that a 90% probability still means one student in ten fails.

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

Norm group: first-takers from LCME-accredited medical schools (US and Canadian through June 2025, US only from July 2025), July 1 2023 - June 30 2026 (N = 67,824). Mean 251 (SD 15) for 2025-2026 first-takers (249 and 250 in the two prior years); SEM about 6. USMLE updates the norms annually.

| 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 |

## Step 1 readiness bands

The cut-offs are StepGenie's own, drawn from community guides (TheMatchGuy, usmlepredictor.com, yousmle, predictmystepscore). "Likely pass, small margin" starts at EPC 64; NBME's guidance says any overlap between the ±4 likely score range and the Step 1 low-pass range warrants extra caution, and from EPC 64 to 69 the range overlaps every published reading of that band. NBME calls a result likely ready only when the whole ±4 range clears the band, about EPC 73-75 under those readings; the 70% mark is TheMatchGuy's reasonable-readiness level.

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

## 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

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

No NBME data rank the forms, and NBME publishes no accuracy figure for predicting a real score from a CCSSA. In step2predictor.com's self-reported r/Step2 data, typical errors differ by under 2 points across forms once timing is accounted for: about 5.3 points for NBME 16 (only 244 reports), 5.9 for NBME 14 and 6.8 for NBME 9, with correlations of 0.67-0.71 for every form. usmlepredictor.com claims r = 0.92 for form 14 but does not disclose its method. Whichever forms you take, the one closest to exam day leaves the least time for your score to change.

### How far off are NBME score predictions?

It depends on what you compare. The ±8 students quote is NBME's likely score range: on a retest without learning or forgetting, you would land within 8 points of this score about two-thirds of the time. It covers measurement error, not what you learn before exam day. Raw totals usually understate the eventual score: in step2predictor.com's self-reported r/Step2 data the mean gain runs 2 to 21 points, by form and timing. After adjusting for timing, that site's model misses by 4.8 points on average and by more than 8 for about one student in six (367 held-out reports, mostly high scorers). Since USMLE's standard error of measurement is about 6 points, even a perfect predictor would average a miss near 5, so the sample likely flatters the model.

### 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 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 practice from the USMLE program itself, run in USMLE's own testing software (USMLE now offers an original and a new Step 2 CK version; use the one that matches your test date), 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 updates the percentile norms annually (the previous edition was dated April 29, 2026); the current edition is dated 2026-08-17 and covers 67,824 first-takers. NBME updates its pass-probability models annually: the CCSSA table was reissued in July 2025 for the 218 standard, and NBME's December 2024 sample CBSSA report cites a model last updated 2024-08-20, so check the date printed on your own report. 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: NBME sells seven CCSSA and seven CBSSA forms, and 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 -- 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 -- Gauging readiness for USMLE Step 1: CBSSA/CBSE guidance (September 2026 edition)](https://www.nbme.org/wp-content/uploads/2024/10/CBSSA_CBSE_Guidance-f43.pdf) (as of 2026-09-01)
- 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)
- 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: [University of Arizona Student Development -- Step 1 FAQs (reads the CBSSA low-pass range as 61-70%)](https://www.studentdevelopment.arizona.edu/step-1-faqs) (as of 2026-09-29)
- 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 2026-08-11)
- 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)
- [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.
- [USMLE Step 1 passing score](https://www.stepgenie.app/usmle/step-1-passing-score) -- what the pass/fail report shows and the last official Step 1 percentile table.
- [Free USMLE self-assessment](https://www.stepgenie.app/self-assessment) -- a practice score to track across forms; no validation against real exam results is published yet.