Free 120 to Step 2 CK conversion
Based on 1,921 real score reports that included a Free 120 result. Scores on this form are reported as a percentage and calibrated directly against real outcomes. Used alone, a Free 120 score predicts the real result with a typical error of about ±6.6 points. Combining two or more tests is meaningfully more accurate.
Each dot is one real report: their Free 120 result against the Step 2 CK score they went on to get. Hover or tap a dot to see that person's full test list. r = 0.68, n = 1,864.
| Free 120 % | Predicted Step 2 CK |
|---|---|
| 55% | 227 |
| 60% | 233 |
| 65% | 239 |
| 70% | 246 |
| 75% | 252 |
| 80% | 258 |
| 85% | 264 |
| 90% | 271 |
| 95% | 277 |
Table and calculator assume the test was taken about 3 days before the exam, the typical timing in our data. Taking it closer to test day shifts the prediction; the full predictor uses your exact timing and every other test you have taken.
Common questions
How is the Free 120 percentage converted?
The conversion is calibrated directly against real outcomes from students who reported both a Free 120 result and their actual Step 2 score.
How accurate is Free 120 alone at predicting Step 2?
A single Free 120 score predicts the real result with a typical error of about ±6.6 points. Combining several practice tests is meaningfully more accurate, which is what the full predictor does.
Get a real prediction, not a rule of thumb
The full predictor combines all of your practice tests with their timing, shows calibrated probability ranges, and was the most accurate of every predictor we benchmarked against real scores. See the head-to-head comparison.