Compare / Claude Opus 4.1 vs GPT-5.5
Claude Opus 4.1 vs GPT-5.5
13 results from 3 sources that measured both models. Each row is in the source's own units; there is no overall winner.
| Benchmark | Metric | Claude Opus 4.1 | GPT-5.5 |
|---|---|---|---|
| Arena (formerly LMArena)reported | OverallArena rating | 1,167 | 1,224 |
| Arena (formerly LMArena)reported | OverallArena rating | 1,435 | 1,486 |
| Arena (formerly LMArena)reported | Business, management and financeArena rating | 1,447 | 1,489 |
| Arena (formerly LMArena)reported | Creative writingArena rating | 1,445 | 1,452 |
| Arena (formerly LMArena)reported | Expert promptsArena rating | 1,482 | 1,513 |
| Arena (formerly LMArena)reported | Instruction followingArena rating | 1,458 | 1,478 |
| Arena (formerly LMArena)reported | OverallArena rating | 1,450 | 1,481 |
| Arena (formerly LMArena)reported | Writing, literature and languageArena rating | 1,446 | 1,470 |
| UGI Leaderboardreported | Requested-length error% off the requested word count | 3.0% | 13.0% |
| UGI Leaderboardreported | Style adherencescore from 0 to 1 | 0.38 | 0.41 |
| UGI Leaderboardreported | Writing scorescore out of 100 | 69.9 | 69.7 |
| Vectara Hallucination Leaderboardreported | Answer rate% of documents | 92.4% | 100.0% |
| Vectara Hallucination Leaderboardreported | Hallucination rate% of summaries | 11.8% | 9.3% |
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.