# Claude Opus 5.5 vs DeepSeek V3.1 Terminus Thinking

As of Oct 15, 2026, Claude Opus 5.5 leads DeepSeek V3.1 Terminus Thinking in 3 of 3 shared categories: General LLM, Reasoning, and Long context.

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

DeepSeek V3.1 Terminus Thinking: price per 1M tokens is unset in the catalog.

Claude Opus 5.5: closed weights.

DeepSeek V3.1 Terminus Thinking: open weights.

- Which to pick, General LLM: As of Oct 15, 2026, Claude Opus 5.5 leads DeepSeek V3.1 Terminus Thinking in General LLM at #2 against #126.
- Which to pick, Reasoning: As of Oct 15, 2026, Claude Opus 5.5 leads DeepSeek V3.1 Terminus Thinking in Reasoning at #1 against #113.
- Which to pick, Long context: As of Oct 15, 2026, Claude Opus 5.5 leads DeepSeek V3.1 Terminus Thinking in Long context at #1 against #88.

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, DeepSeek V3.1 Terminus Thinking is ranked #88 in Long context (since Oct 15, 2026; sources LMArena Text (style-controlled, longer query); methodology v1.0).