NBME Self-Assessments: Every Form, Price, and Which to Take
CBSSA for Step 1, CCSSA for Step 2 CK, CCMSA for Step 3. Compare price, length, and what each score report tells you, then jump to the tool for your form.
NBME self-assessments at a glance
Match the family to your exam first. Form numbers are not interchangeable across families, and each report uses its own scale.
| Assessment | For | Format | Timing | Price | Score report | Use on NBMEcalc |
|---|---|---|---|---|---|---|
| CBSSAComprehensive Basic Science Self-Assessment | Step 1 | 200 questions (4 × 50) | 1 h 15 min per section; self-paced option | From $62 | Total equated percent correct, a likely range, the Step 1 low-pass band, and an estimated probability of passing | CBSSA readiness check |
| CCSSAComprehensive Clinical Science Self-Assessment | Step 2 CK | 200 questions (4 × 50) | 1 h 15 min per section; self-paced option | From $62 | Total CCSSA Score on the 1–300 Step 2 CK scale, a likely score range, and an estimated probability of passing | CCSSA score conversion |
| CCMSAComprehensive Clinical Medicine Self-Assessment | Step 3 | 200 multiple-choice questions (4 × 50); no CCS cases | Up to 1 h 15 min per section; self-paced option | $62 | Assessment Score on a 10–800 scale; NBME states it is not intended to predict Step 3 performance | Step 3 predictor and CCMSA notes |
| CMSClinical Science Mastery Series | Clerkship subjects / Step 2 CK review | 50 questions per subject form | 1 h 15 min; self-paced option | $21 | Subject-level feedback; not a substitute for a comprehensive CCSSA | CMS forms guide |
Checked October 3, 2026 against the NBME CBSSA, CCSSA, and CCMSA product pages and their sample score reports. Prices are NBME's and can change.
Find your NBME form
NBME lists seven CBSSA and seven CCSSA forms for sale; older forms retire as new ones arrive, so check MyNBME for the current set. Pick the form you took to open the matching tool.
Step 1 · CBSSA forms
Readiness check against the official low-pass band.
Forms 26 and 27 are retired, but an older report still works in the same checker.
Step 2 CK · CCSSA forms
Score conversion notes for each form.
Step 3 · CCMSA
CCMSA reports a 10–800 Assessment Score with no official Step 3 conversion. Read why, and estimate Step 3 from UWSA or sample questions, on the Step 3 predictor. For real Step 3 scores, see Step 3 percentiles and passing score.
Free official practice
USMLE's free sample questions (the “Free 120”) report a raw percent only. Check yours with the Free 120 Step 1 readiness check or the Free 120 to Step 2 CK converter.
Which NBME to take first, and how many
NBME does not publish a required order or number of forms. These rules follow from what its own score reports say about reliability.
Start with a baseline
Take one form of the right family early enough that the result can still change your plan. Its content-area feedback shows where to spend the next weeks.
Save fresh forms for the end
Keep at least one unused form for the last one to two weeks. NBME's pass probability is modeled on examinees who tested within a week of the real exam.
Test under real conditions
Use standard pacing and no outside resources. NBME's reports say self-paced timing or looking things up makes the result less reliable for judging readiness.
Do not repeat a form for a score
NBME also notes that retaking the same form makes the report less reliable. Use a different form for each readiness check.
How many? Every score comes with a likely range (about ±4 percentage points on CBSSA, about ±8 points on CCSSA in NBME's sample reports), so two or more recent results that agree are far more convincing than one.
Combine your Step 2 CK results
Enter a current CCSSA Total Score, plus any UWSA, Free 120, or AMBOSS results, to get one planning range. CBSSA and CCMSA reports are read on their own scales using the tools above.
Try the Predictor Live
Add your scores. See your range instantly. No signup.
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How should I interpret an NBME result?
Avoid universal score bands. Reporting differs by assessment family, and an independent estimate does not replace the official score report.
1. Confirm the product
2. Read the official report
3. Check agreement
4. Decide what changes
Why a calculator, when NBME already gives me a number?
Source-aware modelling
The calculator treats comprehensive, subject-level, and third-party inputs differently instead of applying one fixed adjustment to every score.
Multi-source aggregation
One result is not your real ability. We combine compatible CCSSA, UWSA, Free 120, and AMBOSS inputs into a weighted estimate.
Confidence interval
A point estimate without an interval is misleading. We give you an estimated range so you can see the model's uncertainty.
NBME self-assessment FAQs
How much does an NBME self-assessment cost?+
NBME lists CBSSA and CCSSA forms at a price starting from $62 and CCMSA at $62 (checked October 3, 2026). Clinical Science Mastery Series subject forms cost $21. Prices are set by NBME and can change, so confirm in MyNBME before buying.
How many questions are on an NBME self-assessment, and how long does it take?+
CBSSA, CCSSA, and CCMSA each have 200 multiple-choice questions in four sections of 50. Standard pacing allows 1 hour 15 minutes per section, about 5 hours of testing in total. A self-paced option allows up to 5 hours per section.
Which NBME practice exams are for Step 1?+
The NBME practice exams for Step 1 are the Comprehensive Basic Science Self-Assessments (CBSSA). NBME lists seven CBSSA forms for sale. The free alternative is the official USMLE Step 1 sample question set, often called the Free 120.
Which NBME should I take first?+
First choose the correct family: CBSSA for Step 1, CCSSA for Step 2 CK, or CCMSA for Step 3. Within the family, use one form as an early baseline and keep at least one unused form for a final check in the last week or two.
How many NBME practice exams should I take?+
NBME does not prescribe a number. Because every score has a likely range, two or more recent results that agree tell you much more than one. Many students take a baseline plus at least two forms in the final weeks.
Do NBME self-assessments give a pass probability?+
CBSSA and CCSSA reports include an estimated probability of passing Step 1 or Step 2 CK if you test within a week. The CCMSA report does not; it gives a 10–800 Assessment Score and states that it is not intended to predict Step 3 performance.
What score does the CCSSA report?+
The current CCSSA report gives a Total CCSSA Score on the same 1–300 scale as Step 2 CK, plus a likely score range and content-area equated percent correct scores. NBME describes the score as an estimate of your Step 2 CK performance under the same conditions.
How long do I have to use a self-assessment and review it?+
For CBSSA and CCSSA, NBME says the interactive score report and answer explanations stay available for two years after you finish. For CCMSA, NBME says you must complete the assessment within one year of purchase.
Can I retake the same NBME form?+
You can, but NBME's reports state that taking the same form more than once makes the result less reliable for judging readiness. Use a fresh form when you need a new readiness check.
Ready to convert your NBME?
Use the calculator above, or open the conversion guide for your form.