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Step 5 Preview
Grok 4 Fast
Grok 4 Fast is a proprietary model from xAI. It ranks #144 of 351 on the LMArena text leaderboard with a rating of 1407.
LMArena text1407
Rank#144/351
95% interval1399–1415
Votes6.3K
- Developer
- xAI
- Released
- Oct 20, 2026
- Context window
- —
- Price in / out, per 1M tokens
- —
- Weights
- Proprietary
- Inputs
- —
- Reasoning
- —
- Tool use
- —
Benchmarks
| Benchmark | Score bar | Accuracy | Rank | Cost / test |
|---|---|---|---|---|
| SWE-benchCoding | 45.40% | 81 / 85 | $0.05 | |
| Vibe Code BenchCoding | 0.00% | 114 / 115 | $0.13 | |
| LiveCodeBenchCoding | 46.09% | 121 / 143 | $0.2 / $0.5 | |
| MedCodeMedicine | 30.04% | 97 / 107 | $0.2 / $0.5 | |
| MedQAMedicine | 75.36% | 78 / 92 | $0.2 / $0.5 | |
| GPQA DiamondReasoning | 62.12% | 110 / 138 | $0.2 / $0.5 | |
| MMLU-ProReasoning | 70.34% | 120 / 138 | $0.2 / $0.5 | |
| AIMEReasoning | 33.33% | 72 / 96 | $0.2 / $0.5 | |
| MMMUReasoning | 63.41% | 80 / 93 | $0.2 / $0.5 |
Vals AI, as of Oct 24, 2026.
LMArena, by category
| Leaderboard | Rating | Rank | Votes |
|---|---|---|---|
| TextLMArena | 1407 | 144 / 351 | 6.3K |
| CodingLMArena | 1429 | 139 / 346 | 1.2K |
| MathLMArena | 1419 | 126 / 339 | 380 |
| Creative writingLMArena | 1386 | 125 / 349 | 889 |
| Instruction followingLMArena | 1387 | 147 / 351 | 1.7K |
| Hard promptsLMArena | 1412 | 148 / 351 | 3K |
| Multi-turnLMArena | 1414 | 130 / 349 | 1.1K |
| Long queriesLMArena | 1414 | 122 / 330 | 1.4K |
| ExpertLMArena | 1412 | 143 / 305 | 943 |
| Legal and governmentIndustries | 1427 | 119 / 325 | 1.1K |
| Medicine and healthcareIndustries | 1416 | 137 / 325 | 374 |
| Business and financeIndustries | 1394 | 150 / 344 | 3.6K |
| ChineseLanguages | 1457 | 115 / 328 | 463 |
| SpanishLanguages | 1415 | 125 / 249 | 255 |
| GermanLanguages | 1383 | 140 / 261 | 364 |
| FrenchLanguages | 1432 | 118 / 252 | 290 |
| JapaneseLanguages | 1353 | 125 / 236 | 212 |
| WebDevLMArena | 1160 | 149 / 124 | 743 |
LMArena, CC BY 4.0, as of Oct 22, 2026. Where a model is rated at several effort levels, its best is shown (Grok 4 Fast (Non-Reasoning), Grok 4 Fast (Reasoning)).
Compare Grok 4 Fast
xAI
The lab behind Grok, trained on one of the largest compute clusters and integrated with X. Founded 2023, based in San Francisco Bay Area. x.ai
Questions
Who makes Grok 4 Fast?
Grok 4 Fast is made by xAI, founded 2023 and based in San Francisco Bay Area.
How does Grok 4 Fast rank?
#144 of 351 on LMArena’s text leaderboard, rated 1407 (95% interval 1399–1415) from 6,337 votes, as of Oct 22, 2026.
Is Grok 4 Fast open source?
No. Grok 4 Fast is proprietary and served through its provider’s API.