Which Practice Exam Is Most Predictive for Step 2 CK?

Predict My Step Score has predicted 1,212,572 tests, tracking practice scores against real Step 2 CK results for years. In that data, NBME 16 was the most predictive of 15 practice exams.

Wondering which NBME or UWSA to take next? See which practice tests are most predictive.

Most predictive

#1 NBME 16 — the strongest single predictor in our Step 2 CK data.

How to use practice exams for Step 2 CK

Space the NBME forms one to two weeks apart through dedicated study, saving the newest for last. Take UWSA 1 as an early diagnostic and UWSA 2 in the final week or two as the readiness check. The Free 120 is for pacing and the interface, not prediction. In our data NBME 16 was the most predictive single exam; the ranking above shows how far the others fall behind.

All Step 2 CK practice exams

AMBOSS QBank · AMBOSS SA · Free 120 · NBME 9 · NBME 10 · NBME 11 · NBME 12 · NBME 13 · NBME 14 · NBME 15 · NBME 16 · UWorld QBank · UWSA 1 · UWSA 2 · UWSA 3

How this is measured

A paired submission is one student who entered a practice exam score and later reported their actual Step 2 CK result. For each practice exam we fit a regression on every pair and report how much of the variation in real scores it explains (R²). Exams with fewer than 30 pairs are not listed. Data refreshed 2026-05-14.

This is also why a general-purpose AI can't answer this question for you. A prediction is only as good as the paired data behind it — real practice scores matched to the real result those same students went on to get. A chatbot has read the forum threads, but it has never seen verified practice-to-result pairs, so it can only repeat what students remember. Read: ChatGPT is a great medical tutor and a bad score predictor →