Claude Opus 5.5
The model people actually ship agents on: top of the independent index, a price that does not need a budget meeting, and a community that complains mainly about how much it has to be used.
Key facts
- Score
- 91 / 100, rank #1
- Price
- $4 in · $20 out per 1M tokens (Claude pricing)
- Blended price
- $8 per 1M tokens (3 input : 1 output)
- Context window
- 1M
- Open weights
- No
- Released
- Sep 22, 2026
- Best for
- Agentic coding, Long-running agents, Enterprise knowledge work
Claude Opus 5.5 costs $4 per million input tokens and $20 per million output tokens on Anthropic's list price (Claude pricing, read Oct 10, 2026).
Independent evals
| Benchmark | Result | Who ran it | Read |
|---|---|---|---|
| Artificial Analysis Intelligence Index (max) | 58 | Artificial Analysis LLM leaderboard | Oct 9, 2026 |
| Arena text score (high) | 1507 | Arena text leaderboard (Oct 8, 2026) | Oct 9, 2026 |
| Humanity's Last Exam, Diamond (Scale) | 55.0 | Scale SEAL leaderboards | Oct 9, 2026 |
| Epoch Capabilities Index | 167 | Epoch AI benchmarks hub | Oct 9, 2026 |
What practitioners say
The launch thread was the biggest Claude thread of the year on Hacker News, a port of the TypeScript compiler to Rust credited the model with a working build in ten hours, and a Vals AI materials-discovery run used it for agentic simulation. A 'has it been nerfed yet' tracker is the most-upvoted scepticism.
Caveats
- Arena puts Gemini 4 Argon ahead on chat preference; the gap is inside two scores' error bars.
Questions people ask
How much does Claude Opus 5.5 cost?
Claude Opus 5.5 costs $4 per million input tokens and $20 per million output tokens on Anthropic's list price (Claude pricing, read Oct 10, 2026).
How good is Claude Opus 5.5?
Claude Opus 5.5 ranks #1 of 12 on the Models at Work leaderboard with a score of 91 out of 100 (October 2026 edition). The model people actually ship agents on: top of the independent index, a price that does not need a budget meeting, and a community that complains mainly about how much it has to be used.
What is Claude Opus 5.5 best for?
Claude Opus 5.5 is best for agentic coding, long-running agents, enterprise knowledge work.
What are Claude Opus 5.5's benchmark scores?
Artificial Analysis Intelligence Index (max): 58 (Artificial Analysis LLM leaderboard); Arena text score (high): 1507 (Arena text leaderboard (Oct 8, 2026)); Humanity's Last Exam, Diamond (Scale): 55.0 (Scale SEAL leaderboards); Epoch Capabilities Index: 167 (Epoch AI benchmarks hub).
What is Claude Opus 5.5's context window?
Claude Opus 5.5 has a 1M token context window according to Anthropic.
Is Claude Opus 5.5 open weights?
No. Claude Opus 5.5 is a proprietary model available through Anthropic's API and partner clouds.
Compare Claude Opus 5.5
- Claude Opus 5.5 vs GPT-6 Astra
- Claude Opus 5.5 vs Gemini 4 Argon
- Claude Opus 5.5 vs Claude Sonnet 5.5
- Claude Opus 5.5 vs GPT-6.1 Sol
- Claude Opus 5.5 vs Claude Fable 5.1
- Claude Opus 5.5 vs Claude Haiku 5.5
- Claude Opus 5.5 vs Muse Spark 1.3
- Claude Opus 5.5 vs DeepSeek Flash (4.1)
- Claude Opus 5.5 vs GPT-6 Luna
- Claude Opus 5.5 vs Kimi K3
- Claude Opus 5.5 vs Grok 4.7
Methodology: Score is 0 to 100: 50% independent evals normalised within this table, 20% price-performance, 15% practitioner sentiment from Signals and community threads, 15% operational fit (context, speed, availability, open weights). Models within three points are a tie in practice. Vendor-published figures are labelled as such and never counted as independent. Our coverage: read the article.