# Claude Opus 5.5 vs O4 Mini

As of Oct 15, 2026, Claude Opus 5.5 leads O4 Mini in 5 of 5 shared categories: General LLM, Reasoning, Science, Factuality, and Abstraction (ARC).

Claude Opus 5.5: $8.000000000000002 per 1M blended tokens.

O4 Mini: $1.9250000000000003 per 1M blended tokens.

Claude Opus 5.5: closed weights.

O4 Mini: closed weights.

- Which to pick, General LLM: As of Oct 15, 2026, Claude Opus 5.5 leads O4 Mini in General LLM at #2 against #162.
- Which to pick, Reasoning: As of Oct 15, 2026, Claude Opus 5.5 leads O4 Mini in Reasoning at #1 against #168.
- Which to pick, Science: As of Oct 15, 2026, Claude Opus 5.5 leads O4 Mini in Science at #31 against #70.
- Which to pick, Factuality: As of Oct 15, 2026, Claude Opus 5.5 leads O4 Mini in Factuality at #1 against #160.
- Which to pick, Abstraction (ARC): As of Oct 15, 2026, Claude Opus 5.5 leads O4 Mini in Abstraction (ARC) at #1 against #39.

As of Oct 15, 2026, Claude Opus 5.5 is tied for state of the art in Reasoning (since Oct 2, 2026; sources LMArena Text (style-controlled, hard prompts); methodology v1.0).

As of Oct 15, 2026, O4 Mini is a former state-of-the-art holder in Math (since Jul 20, 2025; sources Humanity's Last Exam; methodology v1.0).