Claude Opus 5.5 vs O3 Mini
As of Oct 15, 2026, Claude Opus 5.5 leads O3 Mini in 5 of 5 shared categories: General LLM, Reasoning, Science, Long context, and Abstraction (ARC).
Claude Opus 5.5
Yes. SOTA in Reasoning (tied), Coding (tied), Coding › Agentic (tied), Coding › Web dev, Long context (tied), and Factuality (tied).
O3 Mini
It used to be. Was SOTA in Reasoning.
| Category | Claude Opus 5.5 | O3 Mini |
|---|---|---|
| General LLM | #2 · Near-SOTA · General LLM Margin 1.0638297872340416 LMArena leaderboard dataset · Oct 13, 2026 | #10 · #10 in General LLM Margin — LMArena leaderboard dataset · Apr 16, 2025 |
| Reasoning | #1 · Co-SOTA · Reasoning Margin 0 LMArena leaderboard dataset · Oct 13, 2026 | #172 · Was SOTA · Reasoning Margin 92.02127659574468 LMArena leaderboard dataset · Oct 13, 2026 |
| Math | #— · Not enough data Margin — LMArena leaderboard dataset · Oct 13, 2026 | #— · Not enough data Margin — LMArena leaderboard dataset · Oct 13, 2026 |
| Science | #31 · #31 in Science Margin — Epoch AI benchmarking hub · Sep 22, 2026 | #76 · #76 in Science Margin — Epoch AI benchmarking hub · Jan 31, 2025 |
| Coding | #1 · Co-SOTA · Coding Margin 0 Terminal-Bench Harbor Hub · Oct 6, 2026 | #— · Not enough data Margin — LMArena leaderboard dataset · Oct 13, 2026 |
| Coding › Agentic | #1 · Co-SOTA · Coding › Agentic Margin 0 Terminal-Bench Harbor Hub · Oct 6, 2026 | — |
| Coding › Web dev | #1 · SOTA · Coding › Web dev Margin 0 LMArena leaderboard dataset · Oct 13, 2026 | — |
| Long context | #1 · Co-SOTA · Long context Margin 0 LMArena leaderboard dataset · Oct 13, 2026 | #186 · #186 in Long context Margin 98.93617021276596 LMArena leaderboard dataset · Oct 13, 2026 |
| Vision | #4 · Near-SOTA · Vision Margin 13.15789473684211 Epoch AI benchmarking hub · Sep 22, 2026 | — |
| Factuality | #1 · Co-SOTA · Factuality Margin 0 LMArena leaderboard dataset · Oct 13, 2026 | #— · Not enough data Margin — Epoch AI benchmarking hub · Jan 31, 2025 |
| Abstraction (ARC) | #1 · #1 in Abstraction (ARC) Margin — Epoch AI benchmarking hub · Sep 22, 2026 | #51 · #51 in Abstraction (ARC) Margin — Epoch AI benchmarking hub · Jan 31, 2025 |
Claude Opus 5.5: $8.000000000000002 per 1M blended tokens.
O3 Mini: $1.9250000000000003 per 1M blended tokens.
Claude Opus 5.5: closed weights.
O3 Mini: closed weights.
General LLM: As of Oct 15, 2026, Claude Opus 5.5 leads O3 Mini in General LLM at #2 against #10.
Reasoning: As of Oct 15, 2026, Claude Opus 5.5 leads O3 Mini in Reasoning at #1 against #172.
Science: As of Oct 15, 2026, Claude Opus 5.5 leads O3 Mini in Science at #31 against #76.
Long context: As of Oct 15, 2026, Claude Opus 5.5 leads O3 Mini in Long context at #1 against #186.
Abstraction (ARC): As of Oct 15, 2026, Claude Opus 5.5 leads O3 Mini in Abstraction (ARC) at #1 against #51.
Claude Opus 5.5 or O3 Mini?
As of Oct 15, 2026, Claude Opus 5.5 leads O3 Mini in 5 of 5 shared categories: General LLM, Reasoning, Science, Long context, and Abstraction (ARC).
Claude Opus 5.5 or O3 Mini for General LLM?
As of Oct 15, 2026, Claude Opus 5.5 leads O3 Mini in General LLM at #2 against #10.
Claude Opus 5.5 or O3 Mini for Reasoning?
As of Oct 15, 2026, Claude Opus 5.5 leads O3 Mini in Reasoning at #1 against #172.
Claude Opus 5.5 or O3 Mini for Science?
As of Oct 15, 2026, Claude Opus 5.5 leads O3 Mini in Science at #31 against #76.