Last updated September 1, 2026
The NBME Comprehensive Basic Science Self-Assessment (CBSSA) is the closest thing to an official Step 1 practice exam. It is written by the same organisation that writes the real exam, which is what makes its score estimate worth more than any other.
Each CBSSA form contains 200 multiple-choice items drawn from the same content areas as Step 1. They are self-administered: you buy a form, launch it when ready, and receive a score report with a performance breakdown by content area afterwards.
Several forms are available at any time, and older forms are periodically retired. Because the set changes, check the NBME self-assessments page for the current list rather than relying on a forum post.
Each form is bought individually, in the region of sixty dollars, and NBME periodically offers a discounted bundle of three forms. We are deliberately not quoting an exact figure here: prices change, and the numbers circulating on study blogs frequently disagree with each other. Buy from nbme.org and you will see the current price before you commit.
Budget for three to four forms across a dedicated period. Bundles, where offered, are cheaper than buying individually, and unused forms in a bundle typically remain available for a year.
Since Step 1 became pass/fail, the useful question is not "what will I score" but "am I comfortably clear of the line". A self-assessment gives an estimate with real uncertainty around it, so treat a single result as a range rather than a verdict. A rising trend across three forms tells you far more than any one number.
The content-area breakdown is the part most students underuse. It is the clearest available signal about where the next week of study should go.
Self-assessments measure; question banks teach. They are not substitutes for each other. A common pattern is daily question-bank work for learning, with a self-assessment every week or two as a checkpoint. Because official forms are limited and cost money each time, most people supplement with full-length practice exams from a question bank for the endurance practice, and reserve NBME forms for measurement.
Each Comprehensive Basic Science Self-Assessment form is purchased individually, in the region of sixty dollars, and NBME periodically discounts bundles of three. Check nbme.org for the current price, as figures quoted on study blogs are often out of date.
Three to four across a dedicated period is typical: one early to find your weak areas, one or two through the middle, and one about a week before the exam.
They are written by the same organisation and drawn from the same content areas, which is why their score estimates carry more weight than other practice exams. Each form has 200 items, fewer than the real exam.
No. Any single score carries real uncertainty. A rising trend across three forms is a much better readiness signal than one result in isolation.
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