Claude Opus 5.5 vs Claude Sonnet 4.5
As of Oct 15, 2026, Claude Opus 5.5 leads Claude Sonnet 4.5 in 7 of 7 shared categories: General LLM, Reasoning, Science, Coding › Web dev, Long context, Factuality, 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).
Claude Sonnet 4.5
It used to be. Was SOTA in General LLM.
| Category | Claude Opus 5.5 | Claude Sonnet 4.5 |
|---|---|---|
| General LLM | #2 · Near-SOTA · General LLM Margin 1.0638297872340416 LMArena leaderboard dataset · Oct 13, 2026 | #62 · Was SOTA · General LLM Margin 32.97872340425532 LMArena leaderboard dataset · Oct 13, 2026 |
| Reasoning | #1 · Co-SOTA · Reasoning Margin 0 LMArena leaderboard dataset · Oct 13, 2026 | #51 · Was SOTA · Reasoning Margin 27.65957446808511 LMArena leaderboard dataset · Oct 13, 2026 |
| Math | #— · Not enough data Margin — LMArena leaderboard dataset · Oct 13, 2026 | #25 · #25 in Math Margin 53.333333333333336 Epoch AI benchmarking hub · Sep 29, 2025 |
| Science | #31 · #31 in Science Margin — Epoch AI benchmarking hub · Sep 22, 2026 | #82 · #82 in Science Margin — Epoch AI benchmarking hub · Sep 29, 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 | #86 · Was SOTA · Coding › Web dev Margin 68 LMArena leaderboard dataset · Oct 13, 2026 |
| Long context | #1 · Co-SOTA · Long context Margin 0 LMArena leaderboard dataset · Oct 13, 2026 | #34 · Was SOTA · Long context Margin 18.085106382978722 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 | #61 · #61 in Factuality Margin 36.04651162790697 LMArena leaderboard dataset · Oct 13, 2026 |
| Abstraction (ARC) | #1 · #1 in Abstraction (ARC) Margin — Epoch AI benchmarking hub · Sep 22, 2026 | #66 · #66 in Abstraction (ARC) Margin — Epoch AI benchmarking hub · Sep 29, 2025 |
Claude Opus 5.5: $8.000000000000002 per 1M blended tokens.
Claude Sonnet 4.5: $6 per 1M blended tokens.
Claude Opus 5.5: closed weights.
Claude Sonnet 4.5: closed weights.
General LLM: As of Oct 15, 2026, Claude Opus 5.5 leads Claude Sonnet 4.5 in General LLM at #2 against #62.
Reasoning: As of Oct 15, 2026, Claude Opus 5.5 leads Claude Sonnet 4.5 in Reasoning at #1 against #51.
Science: As of Oct 15, 2026, Claude Opus 5.5 leads Claude Sonnet 4.5 in Science at #31 against #82.
Coding › Web dev: As of Oct 15, 2026, Claude Opus 5.5 leads Claude Sonnet 4.5 in Coding › Web dev at #1 against #86.
Long context: As of Oct 15, 2026, Claude Opus 5.5 leads Claude Sonnet 4.5 in Long context at #1 against #34.
Factuality: As of Oct 15, 2026, Claude Opus 5.5 leads Claude Sonnet 4.5 in Factuality at #1 against #61.
Abstraction (ARC): As of Oct 15, 2026, Claude Opus 5.5 leads Claude Sonnet 4.5 in Abstraction (ARC) at #1 against #66.
Claude Opus 5.5 · Claude Sonnet 4.5
Claude Opus 5.5 or Claude Sonnet 4.5?
As of Oct 15, 2026, Claude Opus 5.5 leads Claude Sonnet 4.5 in 7 of 7 shared categories: General LLM, Reasoning, Science, Coding › Web dev, Long context, Factuality, and Abstraction (ARC).
Claude Opus 5.5 or Claude Sonnet 4.5 for General LLM?
As of Oct 15, 2026, Claude Opus 5.5 leads Claude Sonnet 4.5 in General LLM at #2 against #62.
Claude Opus 5.5 or Claude Sonnet 4.5 for Reasoning?
As of Oct 15, 2026, Claude Opus 5.5 leads Claude Sonnet 4.5 in Reasoning at #1 against #51.
Claude Opus 5.5 or Claude Sonnet 4.5 for Science?
As of Oct 15, 2026, Claude Opus 5.5 leads Claude Sonnet 4.5 in Science at #31 against #82.