Model comparison
Grok 4 Fast vs Step 5 Preview
Step 5 Preview is the stronger model overall, scoring 47.9 to 39.4 on the Noometry Index.
Last verified . 14 shared benchmarks.
StepFunSummary
- They share 14 benchmarks with published results for both. Grok 4 Fast scores higher in 1 category and Step 5 Preview in 7 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in coding, where Step 5 Preview leads 51.8 to 32.5.
Side by side
| Grok 4 Fast | Step 5 Preview | |
|---|---|---|
| Provider | xAI | StepFun |
| Noometry Index | 39.4 | 47.9 |
| Released | 2025-09-19 | 2026-09-16 |
| Weights | Proprietary | Proprietary |
| Context window | — | 1.02M |
| Max output | — | 66K |
| Input $ / M tokens | — | $1 |
| Output $ / M tokens | — | $2.70 |
| Results tracked | 30 | 18 |
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Category by category
Coding Step 5 Preview leads
Grok 4 Fast: 32.5 (#271), Step 5 Preview: 51.8 (#36)
| Benchmark | Grok 4 Fast | Step 5 Preview |
|---|---|---|
| LMArena WebDev | 1159 | 1564 |
| LMArena Coding | 1429 | 1480 |
| SciCode | — | 58.9% |
| WeirdML | 42.9% | — |
Agentic & Tool Use Not comparable
Grok 4 Fast: 29.5 (#86), Step 5 Preview: —
| Benchmark | Grok 4 Fast | Step 5 Preview |
|---|---|---|
| τ²-bench Banking | 15.7% | — |
| Cybench | 30% | — |
| LMArena Search | 1171 | — |
Reasoning Step 5 Preview leads
Grok 4 Fast: 22.2 (#201), Step 5 Preview: 40.0 (#57)
| Benchmark | Grok 4 Fast | Step 5 Preview |
|---|---|---|
| LMArena Hard Prompts | 1412 | 1465 |
| ARC-AGI-2 | 5.3% | — |
| Kagi LLM Benchmark | 66.1% | — |
| ARC-AGI-1 | 48.5% | — |
| CritPt | — | 20.9% |
| DTBench | 82.7% | — |
| Epoch Capabilities Index | 144.2 | — |
| ForecastBench | 60.5 | — |
Math Step 5 Preview leads
Grok 4 Fast: 38.9 (#123), Step 5 Preview: 46.1 (#72)
| Benchmark | Grok 4 Fast | Step 5 Preview |
|---|---|---|
| LMArena Math | 1419 | 1470 |
| ProofBench | — | 42% |
Knowledge Step 5 Preview leads
Grok 4 Fast: 32.0 (#214), Step 5 Preview: 41.2 (#112)
| Benchmark | Grok 4 Fast | Step 5 Preview |
|---|---|---|
| LMArena Expert | 1411 | 1470 |
| Vectara Hallucination Rate | 19.7% | — |
Multimodal Not comparable
Grok 4 Fast: —, Step 5 Preview: 41.0 (#41)
| Benchmark | Grok 4 Fast | Step 5 Preview |
|---|---|---|
| LMArena Vision | — | 1267 |
Multilingual Step 5 Preview leads
Grok 4 Fast: 51.3 (#111), Step 5 Preview: 53.8 (#54)
| Benchmark | Grok 4 Fast | Step 5 Preview |
|---|---|---|
| LMArena Non-English | 1396 | 1432 |
| LMArena Chinese | 1457 | 1519 |
| LMArena Russian | 1389 | 1436 |
| LMArena Spanish | 1415 | 1439 |
| LMArena French | 1431 | — |
| LMArena German | 1383 | — |
| LMArena Japanese | 1352 | — |
| LMArena Korean | 1357 | — |
Instruction Following Step 5 Preview leads
Grok 4 Fast: 73.2 (#121), Step 5 Preview: 76.0 (#50)
| Benchmark | Grok 4 Fast | Step 5 Preview |
|---|---|---|
| LMArena Instruction Following | 1387 | 1444 |
Long Context Grok 4 Fast leads
Grok 4 Fast: 63.2 (#3), Step 5 Preview: 44.5 (#64)
| Benchmark | Grok 4 Fast | Step 5 Preview |
|---|---|---|
| LMArena Longer Query | 1415 | 1455 |
| Fiction.LiveBench | 94.4% | — |
Writing & Preference Step 5 Preview leads
Grok 4 Fast: 60.0 (#102), Step 5 Preview: 62.8 (#71)
| Benchmark | Grok 4 Fast | Step 5 Preview |
|---|---|---|
| LMArena Text | 1407 | 1442 |
| LMArena Creative Writing | 1387 | 1410 |
| LMArena Multi-Turn | 1414 | 1447 |
Frequently asked questions
Is Grok 4 Fast better than Step 5 Preview?
Step 5 Preview is the stronger model overall, scoring 47.9 to 39.4 on the Noometry Index.
Is Grok 4 Fast or Step 5 Preview better for coding?
Step 5 Preview scores higher on coding benchmarks: 51.8 versus 32.5 in the Noometry coding category.
How many benchmarks do Grok 4 Fast and Step 5 Preview share?
14 benchmarks have published results for both models. Grok 4 Fast has 30 scored results on Noometry and Step 5 Preview has 18.