Free 120 Score CalculatorStep 1's Only Official Free Practice Exam — What Your % Correct Predicts
120 questions · 3 blocks · The NBME's official free assessment. Enter your wrong answers to get your predicted Step 1 score from the Free 120 formula — then read the interpretation guide below. Free 120 is best used for interface rehearsal and as a secondary readiness signal, not a standalone predictor.
High Variance Predictor — Use Alongside Paid NBME Forms, Not Instead
Free 120 has the lowest predictive accuracy (R² = 0.47) of any commonly used Step 1 practice exam. Individual scores vary by ±10–15 points from actual Step 1. Use this result as a secondary data point — not a standalone scheduling signal. If your Free 120 result conflicts sharply with recent paid NBME forms, trust the paid forms.
What Free 120 Gives You — and What It Doesn't
- Percentage correct per block (e.g., 73% correct)
- Overall % correct for the full 120-question set
- Right/wrong answer feedback after submission
- Interface experience identical to the real Step 1 exam
- No 3-digit predicted score from NBME itself
- No scaled equated score or pass probability
- No subscores by subject or system
- No official explanations (third-party resources exist)
This calculator bridges the gap — converting your wrong answer count to a community-derived predicted 3-digit score. The formula (Score = 269.25 − 1.207 × wrong answers) is derived from a large Reddit r/step1 regression dataset, not from NBME. Treat the output as an estimate with ±10–15 points of individual variance.
How Reliable Is Free 120 as a Step 1 Predictor?
| Metric | Free 120 | Paid NBME (28–31) | UWSA 2 |
|---|---|---|---|
| Predictive R² | ~0.47 | 0.70–0.85 | ~0.85 |
| Variance | ±10–15 pts | ±5–8 pts | ±5 pts |
| Score output | % correct only | Predicted score | Predicted score |
| Primary use | Interface rehearsal | Readiness signal | Scheduling decision |
R² = 0.47 means Free 120 accounts for only about half of the real variance in Step 1 scores. Two students with identical Free 120 scores can differ by 20+ points on the real exam. This is expected — Free 120 is not psychometrically equated for score prediction; it is calibrated to mirror the exam's content style and interface.
Free 120 Format vs. Real Step 1 — Key Differences
| Free 120 | Real Step 1 | |
|---|---|---|
| Total questions | 120 | Up to 280 |
| Blocks | 3 × 40 questions | Up to 7 × 40 questions |
| Time per block | 60 min | 60 min |
| Total seated time | ~3 hours | ~8 hours |
| Score output | % correct | Pass / Fail |
| Subscores | None | None |
| Question pool | Fixed (updated periodically) | Randomized from pool |
The April 2026 version added questions in cardiology, rheumatology, hematology, and neurology. Question overlap with the real Step 1 exam is possible but not guaranteed.
Free 120 Score Benchmarks — Wrong Answers, % Correct, Predicted Score
Community consensus: scoring ≥66% correct (≤41 wrong) is a reassuring sign. Below 60% correct (≥48 wrong), validate immediately with a paid NBME form.
| Wrong | % Correct | Predicted Score | Signal |
|---|---|---|---|
| 12 | 90% | ~255 | Exceptional |
| 24 | 80% | ~240 | Strong |
| 36 | 70% | ~226 | Above passing — good sign |
| 41 | 65.8% | ~220 | Community "passing zone" floor |
| 48 | 60% | ~211 | Below community threshold — validate |
| 60 | 50% | ~197 | Formula passing threshold — high risk |
| 72 | 40% | ~182 | Below passing — do not schedule |
Free 120 score formula: 269.25 − 1.207 × wrong answers (derived from community regression; R² = 0.47). Passing threshold: 196. Individual variance ±10–15 pts.
How to Use Free 120 in Your Dedicated Period
Interface Rehearsal — Primary Value
The Free 120 replicates the exact Step 1 software interface: navigation, flagging, exhibits, lab panels, calculator, and break timer. Taking it 4–7 days before your exam means you can skip the 15-minute built-in tutorial on test day — recovering 15 minutes of buffer time. This alone makes Free 120 worth taking regardless of your predicted score.
Readiness Triangulation — Secondary Value
If your Free 120 result is broadly consistent with recent paid NBME results (within 10 points), treat it as a confirmatory signal. If there is a sharp discrepancy — e.g., 65% Free 120 but 250+ on recent paid NBMEs — trust the paid forms. A single-form outlier at this level of R² is usually noise, not signal.
Best timing: 4–7 days before exam
Community consensus: Blueprint Prep says 4–5 days; MDSteps says 3–7 days; Mehlman Medical says 7–10 days. Earlier is fine if taken for interface practice; closer to exam day preserves maximum diagnostic value.
Free 120 vs. NBME 29 / 30 / 31 — Choosing the Right Predictor
| Free 120 | NBME 29 | NBME 30 | NBME 31 | |
|---|---|---|---|---|
| Questions | 120 | 200 | 200 | 200 |
| Predictive R² | ~0.47 | ~0.78 | ~0.80 | ~0.75 |
| Score output | % correct only | Predicted score | Predicted score | Predicted score |
| Variance | ±10–15 pts | ±5–8 pts | ±5–8 pts | ±5–8 pts |
| Cost | Free | $35 | $35 | $35 |
| Primary use | Interface rehearsal | Readiness check | Final checkpoint | Content check |
| Recommended timing | 4–7 days before | Week 6–7 | Final 1–2 wks | Final 1–2 wks |
R² estimates reflect community-derived regressions; no peer-reviewed study has published form-specific R² data for NBME 29–31.
Free 120 Score Conversion Table — Step 1
| Wrong | Correct | % Correct | Predicted Score | Pass Prob |
|---|---|---|---|---|
| 0 | 120 | 100% | 269 | 99.9% |
| 5 | 115 | 95.8% | 263 | 99.9% |
| 10 | 110 | 91.7% | 257 | 99.9% |
| 15 | 105 | 87.5% | 251 | 99.9% |
| 20 | 100 | 83.3% | 245 | 99.9% |
| 25 | 95 | 79.2% | 239 | 99.9% |
| 30 | 90 | 75% | 233 | 99.9% |
| 35 | 85 | 70.8% | 227 | 99.6% |
| 40 | 80 | 66.7% | 221 | 98.9% |
| 45 | 75 | 62.5% | 215 | 96.8% |
| 50 | 70 | 58.3% | 209 | 91.2% |
| 55 | 65 | 54.2% | 203 | 77.9% |
| 60 | 60 | 50% | 197 | 54.5% |
| 65 | 55 | 45.8% | 191 | 28.9% |
| 70 | 50 | 41.7% | 185 | 12.1% |
| 75 | 45 | 37.5% | 179 | 4.5% |
| 80 | 40 | 33.3% | 173 | 1.6% |
| 85 | 35 | 29.2% | 167 | 0.5% |
| 90 | 30 | 25% | 161 | 0.2% |
| 95 | 25 | 20.8% | 155 | 0.1% |
| 100 | 20 | 16.7% | 149 | 0.1% |
| 105 | 15 | 12.5% | 143 | 0.1% |
| 110 | 10 | 8.3% | 140 | 0.1% |
| 115 | 5 | 4.2% | 140 | 0.1% |
| 120 | 0 | 0% | 140 | 0.1% |
About Free 120
Official NBME free practice exam — format rehearsal.
Best for interface familiarity. Wide individual variance (±10–15 pts). Use as a tiebreaker, not primary predictor.
Other Step 1 Practice Exams
Free 120 Step 1 Calculator — FAQ
This tool is for educational purposes only. Not affiliated with NBME® or USMLE®. Predicted scores are derived from a community regression model (R² = 0.47) and carry an estimated individual variance of ±10–15 points. No peer-reviewed study has published form-specific accuracy data for the Free 120. Always validate with a paid NBME CBSSA form before making scheduling decisions.