Claude Opus 5 vs GPT-5.5

On LM Arena, Claude Opus 5 has 1494 Elo and GPT-5.5 has 1481 Elo. Claude Opus 5 has the higher displayed score on this source. Each source stands on its own; these scores do not establish an overall winner.

Claude Opus 5: 1494 Elo on LM Arena (19,353 Arena votes) (snapshot Aug 12, 2026). GPT-5.5: 1481 Elo on LM Arena (55,130 Arena votes) (snapshot Aug 12, 2026). The snapshots may have been collected on different dates.