NBME and Free 120 score converter
For NBME 9 through 16, convert raw percent correct to a 3-digit form score or work backward from the 3-digit score. For Old Free 120 (2021) and New Free 120 (2023), enter the percentage to get a predicted Step 2 CK score. Free 120 does not have an official 3-digit assessment score.
≈ — predicted on Step 2 CKrefine with timing and other tests →
Based on real reports listing both a percent and a 3-digit NBME 14 score, combined with published conversions (typically within about ±3 points).
Predictions use each assessment's typical timing; the main predictor uses your exact timing and every other test. See the full breakdown for each assessment: NBME 9 · NBME 10 · NBME 11 · NBME 12 · NBME 13 · NBME 14 · NBME 15 · NBME 16 · Old Free 120 (2021) · New Free 120 (2023).
How the conversion works
When you take an NBME self-assessment online, NBME turns your raw performance into a 3-digit score with a fixed, form-specific scoring table. Offline takers only have a percent correct. This tool estimates the relationship using about 2.2 points per percent, then accounts for small differences in difficulty between forms. The estimate was built from r/Step2 reports that listed both a percent and a 3-digit score, then combined with published conversions. Free 120 is different: its percentage is converted directly to a predicted Step 2 CK score using reports that included both results.
Common questions
How do I convert an NBME percent correct to a 3-digit score?
Pick your form and enter your raw percent correct. NBME Step 2 forms have 200 questions, so each is worth about half a percent. The tool maps your percent to the 3-digit form score (about 2.2 points per percent, based on real reports and combined with published conversions), then to a predicted Step 2 CK score. You can also enter a 3-digit score to calculate the equivalent percent correct.
Why does the same percent give a different score on different forms?
Each NBME form has its own scoring curve, so a given percent maps to a slightly different 3-digit score depending on the form. The differences are small (usually within a couple of points), but the converter applies the specific curve for the form you select.
How accurate is the NBME percent-to-score conversion?
On forms with enough reports, the conversion was rebuilt for each student in turn without that student's report, then checked against it. The typical difference was about 2 to 3 points. NBME 15 has fewer reports, and NBME 16 is based on the relationship seen across Forms 9 through 15.
How are Old and New Free 120 percentages converted?
Free 120 results are percentages, not official 3-digit assessment scores. Select Old Free 120 (2021) or New Free 120 (2023), then enter the percentage to get a predicted Step 2 CK score based on students who reported both results.
Combine your scores
Combine your practice scores and test dates in the full predictor. Open the predictor →
Charts & guides
Browse the score analyses, study-data pages, and assessment converters.