CBSSA. CBSE. Free 120. Self-paced. Standard-paced. If you've tried to figure out which official practice exams you actually need for Step 1, you've probably ended up with ten browser tabs open and less clarity than when you started.
It doesn't help that everyone in your class has a slightly different plan, and every plan comes with a confident explanation of why theirs is the right one.
The good news: the official options are simpler than the acronyms make them look. Here's what each one is, how many you need, and how to schedule them so they actually guide your prep.
What Are the NBME Practice Exams for Step 1?
There are three official options. The main one is the CBSSA (Comprehensive Basic Science Self-Assessment): NBME currently offers 7 forms, with prices starting at $62 per form. Each standard-paced form is 4 sections of 50 questions, 1 hour 15 minutes per section, and the score report gives you an estimated probability of passing Step 1 plus an equated percent correct. The second is the Free 120, a free set of official sample questions. The third is the CBSE, a comprehensive exam some medical schools administer to their students.
For most students, a solid plan is a baseline CBSSA early in dedicated, two to four more spread across it, and the Free 120 in the final week. Since Step 1 is pass/fail with a passing standard of 196, these NBME practice exams for Step 1 matter less as score chasers and more as an early-warning system: they tell you whether you're on track while there's still time to adjust.
Outside the official set, MedSchoolGuru also offers a free Step 1 Free 120 diagnostic on MedSchoolGuru: 120 timed questions with a scaled score estimate and pass-likelihood readout. It doesn't replace your NBME forms, but it's a no-cost extra data point, especially early in dedicated before you start paying for CBSSAs.
The CBSSA: The Main Event
What You're Actually Buying
Each CBSSA form is a 200-question, exam-style assessment built by NBME. You choose standard-paced (timed, 1 hour 15 minutes per 50-question section) or self-paced (more time per section). With 7 forms available, you have more than enough to cover dedicated without repeating any.
What the Score Report Tells You
Two numbers do most of the work. The estimated probability of passing is the headline in the pass/fail era: it answers the question you actually care about. The equated percent correct (EPC) lets you compare performance across forms on a consistent footing, which makes it great for tracking your trend over time. You'll also see a breakdown of relative strengths and weaknesses by content area, which is the best map you'll get of where your remaining study time should go.
Standard-Paced vs. Self-Paced
If you want the results to reflect test-day readiness, take it standard-paced. Self-paced has a place early on, when you're using a form purely as a learning tool, but the extra time makes the pass estimate less meaningful. When in doubt, use timed conditions.
The Free 120 and the CBSE
The Free 120
The Free 120 is a free set of official sample questions available on the NBME orientation site. It doesn't give you a score report or pass estimate, only percent correct, but it's the closest look you'll get at current official question style and the real testing interface. Most students take it timed in the last 3 to 10 days before the exam.
The CBSE
The CBSE is a comprehensive basic science exam that medical schools administer to their own students. Some schools use it as a checkpoint before they'll certify you to sit for Step 1. You don't buy it yourself. If your school offers it, it's a useful data point. If it requires a certain result before dedicated ends, know that benchmark early and plan your CBSSA schedule around it.
How to Schedule NBME Practice Exams During Dedicated
Week 1: Take a Baseline
Take your first CBSSA at the very start of dedicated, even if you feel unready. Especially if you feel unready. A baseline tells you which systems need the most time and how far you are from comfortable passing territory.
The Middle Weeks: One Form Every 1 to 2 Weeks
Space your next forms roughly every week or two. That's enough time to act on what each report shows before you test again. Taking forms back-to-back without changing anything in between just measures the same version of you twice.
The Final Two Weeks: Last CBSSA, Then the Free 120
Take your last CBSSA about one to two weeks before test day, then the Free 120 a few days to a week out. Many students save the most recently released forms for last, on the theory that they best reflect current question style. That's community advice rather than NBME guidance, but it's a reasonable way to order them.
Review Days Count as Much as Test Days
Block out a full review day after every form. Review every question, including the ones you got right, and sort misses into knowledge gaps, misreads and timing errors. The review is where the improvement happens.
If you're still deciding how long your dedicated block should be, our guide on how long to study for Step 1 walks through it.
How to Read Your Results in the Pass/Fail Era
Focus on the trend, not any single form. Two or three consecutive forms showing a high estimated probability of passing is a much stronger signal than one great day. A single dip after several strong forms is usually noise, often a tough form or a bad night of sleep.
A borderline or falling probability across multiple forms is different. That's the signal to change something: shift time toward your weakest content areas, increase question volume, and talk to your school advisor about whether your test date still makes sense. Keep the stakes in mind. In 2024, 91% of US MD first-time takers passed Step 1, compared with roughly 70% of repeaters, so moving your date when the data says you're not ready is usually smarter than hoping it works out.
What Most Students Get Wrong About NBME Practice Exams
The first mistake is avoiding the baseline. Students put off their first CBSSA because they're afraid of the number, then lose weeks they could have spent fixing the exact weaknesses it would have revealed.
The second is treating practice exams as the study plan. NBME practice exams for Step 1 measure readiness; they don't build it. If you're taking a form every few days and spending little time on questions and review in between, you're testing more and improving less.
The third is mixing conditions. Taking one form self-paced, one timed, and one half-distracted at a coffee shop makes the trend almost impossible to read. Same conditions every time, as close to test day as you can make them.
The last is obsessing over a single result. Your plan should respond to patterns across several forms, not to the emotional weight of one.
Filling the Gaps Between Your NBMEs
Your CBSSA reports tell you where the gaps are. What closes them is high-quality question practice in the weeks between forms. The Step 1 Question Bank from MedSchoolBro gives you 2,500+ NBME-style questions and 6 CBSE-style diagnostic exams, so you can target the weak areas each report flags and check your progress in between official forms.
Frequently Asked Questions
How many NBME practice exams should I take for Step 1? Most students do well with three to five CBSSA forms across dedicated plus the Free 120 in the final week. There are 7 CBSSA forms available, so you won't run out. More isn't automatically better if it squeezes out review time.
Are NBME practice exams accurate for Step 1? They're the official self-assessments from the organization that co-sponsors the exam, so they're the most credible readiness signal you can get. No practice test guarantees an outcome, but a consistent trend of high pass probability across several forms is a strong sign you're ready.
Which NBME practice exam should I take first? Any CBSSA form works as a baseline at the start of dedicated. Many students save the most recently released forms for the final weeks, since they're thought to best reflect current question style, and take the Free 120 last.
Should I take the CBSSA timed or self-paced? Timed (standard-paced) whenever you want a meaningful readiness estimate. Self-paced can work as a learning tool early on, but the extra time makes the pass estimate less representative of test-day conditions.
