Compare / GPT-5.1 vs grok-4-fast-reasoning
GPT-5.1 vs grok-4-fast-reasoning
12 results from 3 sources that measured both models. Each row is in the source's own units; there is no overall winner.
| Benchmark | Metric | GPT-5.1 | grok-4-fast-reasoning |
|---|---|---|---|
| Arena (formerly LMArena)reported | OverallArena rating | 1,459 | 1,417 |
| Arena (formerly LMArena)reported | Business, management and financeArena rating | 1,448 | 1,403 |
| Arena (formerly LMArena)reported | Creative writingArena rating | 1,428 | 1,383 |
| Arena (formerly LMArena)reported | Expert promptsArena rating | 1,482 | 1,421 |
| Arena (formerly LMArena)reported | Instruction followingArena rating | 1,450 | 1,389 |
| Arena (formerly LMArena)reported | OverallArena rating | 1,456 | 1,405 |
| Arena (formerly LMArena)reported | Writing, literature and languageArena rating | 1,437 | 1,388 |
| UGI Leaderboardreported | Requested-length error% off the requested word count | 113.0% | 23.0% |
| UGI Leaderboardreported | Style adherencescore from 0 to 1 | 0.38 | 0.33 |
| UGI Leaderboardreported | Writing scorescore out of 100 | 55.8 | 53.4 |
| Vectara Hallucination Leaderboardreported | Answer rate% of documents | 100.0% | 99.5% |
| Vectara Hallucination Leaderboardreported | Hallucination rate% of summaries | 10.9% | 20.2% |
Bold green marks the better value on that metric. Where a source reports ranges that overlap, the difference may not be meaningful; see the benchmark page for ranges.