Model comparison
Grok 4 Fast vs Step 3
Step 3 is the stronger model overall, scoring 40.5 to 39.4 on the Noometry Index.
Last verified . 16 shared benchmarks.
StepFunSummary
- They share 16 benchmarks with published results for both. Grok 4 Fast scores higher in 5 categories and Step 3 in 3 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in long context, where Grok 4 Fast leads 63.2 to 40.3.
- Step 3 has downloadable open weights; the other is API-only.
Side by side
| Grok 4 Fast | Step 3 | |
|---|---|---|
| Provider | xAI | StepFun |
| Noometry Index | 39.4 | 40.5 |
| Released | 2025-09-19 | — |
| Weights | Proprietary | Open |
| Context window | — | — |
| Max output | — | — |
| Input $ / M tokens | — | — |
| Output $ / M tokens | — | — |
| Results tracked | 30 | 17 |
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Category by category
Coding Step 3 leads
Grok 4 Fast: 32.5 (#271), Step 3: 40.1 (#147)
| Benchmark | Grok 4 Fast | Step 3 |
|---|---|---|
| LMArena Coding | 1429 | 1367 |
| LMArena WebDev | 1159 | — |
| WeirdML | 42.9% | — |
Agentic & Tool Use Not comparable
Grok 4 Fast: 29.5 (#86), Step 3: —
| Benchmark | Grok 4 Fast | Step 3 |
|---|---|---|
| τ²-bench Banking | 15.7% | — |
| Cybench | 30% | — |
| LMArena Search | 1171 | — |
Reasoning Step 3 leads
Grok 4 Fast: 22.2 (#201), Step 3: 28.4 (#105)
| Benchmark | Grok 4 Fast | Step 3 |
|---|---|---|
| Kagi LLM Benchmark | 66.1% | 62.3% |
| LMArena Hard Prompts | 1412 | 1355 |
| ARC-AGI-2 | 5.3% | — |
| ARC-AGI-1 | 48.5% | — |
| DTBench | 82.7% | — |
| Epoch Capabilities Index | 144.2 | — |
| ForecastBench | 60.5 | — |
Math Grok 4 Fast leads
Grok 4 Fast: 38.9 (#123), Step 3: 37.6 (#148)
| Benchmark | Grok 4 Fast | Step 3 |
|---|---|---|
| LMArena Math | 1419 | 1366 |
Knowledge Step 3 leads
Grok 4 Fast: 32.0 (#214), Step 3: 36.8 (#164)
| Benchmark | Grok 4 Fast | Step 3 |
|---|---|---|
| LMArena Expert | 1411 | 1333 |
| Vectara Hallucination Rate | 19.7% | — |
Multimodal Not comparable
Grok 4 Fast: —, Step 3: 35.5 (#86)
| Benchmark | Grok 4 Fast | Step 3 |
|---|---|---|
| LMArena Vision | — | 1177 |
Multilingual Grok 4 Fast leads
Grok 4 Fast: 51.3 (#111), Step 3: 46.3 (#159)
| Benchmark | Grok 4 Fast | Step 3 |
|---|---|---|
| LMArena Non-English | 1396 | 1327 |
| LMArena Chinese | 1457 | 1397 |
| LMArena German | 1383 | 1371 |
| LMArena Korean | 1357 | 1269 |
| LMArena Russian | 1389 | 1331 |
| LMArena Spanish | 1415 | 1371 |
| LMArena French | 1431 | — |
| LMArena Japanese | 1352 | — |
Instruction Following Grok 4 Fast leads
Grok 4 Fast: 73.2 (#121), Step 3: 70.4 (#164)
| Benchmark | Grok 4 Fast | Step 3 |
|---|---|---|
| LMArena Instruction Following | 1387 | 1332 |
Long Context Grok 4 Fast leads
Grok 4 Fast: 63.2 (#3), Step 3: 40.3 (#157)
| Benchmark | Grok 4 Fast | Step 3 |
|---|---|---|
| LMArena Longer Query | 1415 | 1326 |
| Fiction.LiveBench | 94.4% | — |
Writing & Preference Grok 4 Fast leads
Grok 4 Fast: 60.0 (#102), Step 3: 54.3 (#151)
| Benchmark | Grok 4 Fast | Step 3 |
|---|---|---|
| LMArena Text | 1407 | 1350 |
| LMArena Creative Writing | 1387 | 1321 |
| LMArena Multi-Turn | 1414 | 1341 |
Frequently asked questions
Is Grok 4 Fast better than Step 3?
Step 3 is the stronger model overall, scoring 40.5 to 39.4 on the Noometry Index.
Is Grok 4 Fast or Step 3 better for coding?
Step 3 scores higher on coding benchmarks: 40.1 versus 32.5 in the Noometry coding category.
How many benchmarks do Grok 4 Fast and Step 3 share?
16 benchmarks have published results for both models. Grok 4 Fast has 30 scored results on Noometry and Step 3 has 17.