Anthropic · llm model

Claude Opus 5.5

Claude Opus 5.5 is an Anthropic language model released Sep 22, 2026; Anthropic's newest language model in our dataset is Claude Haiku 5.5. Proprietary, API access only. Anthropic's recommended starting model for most workloads, which Anthropic says leads in agentic coding and knowledge work. Verified against vendor sources on Oct 26, 2026.

Reported Last verified Oct 26, 2026 · All models · JSON · Markdown

ReleasedSep 22, 2026
Context window1M1,000,000 tokens
Max output128K128,000 tokens
LicenceProprietaryProprietary (API)

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Key facts

Claude Opus 5.5: key facts with sources
Fact	Value	Source
Vendor	Anthropic	n/a
Released	Sep 22, 2026	source
Status	generally available	n/a
API id	claude-opus-5-5	source
Context window	1,000,000 tokens (1M)	source
Max output	128,000 tokens	source
Input	text, image	source
Output	text	source
Licence	Proprietary (API)	source
Pricing	$4 in / $20 out per 1M tokens	source

Where Claude Opus 5.5 sits in our data

Released Sep 22, 2026 (week 39 of 2026), in September 2026. Other models in our data released that month: GPT-6.1 Sol, Claude Sonnet 5.5, Gemini 3.8 Flash TTS, Gemini 3.8 Flash-Lite TTS, GPT-6 Luna, GPT-6 Sol.
The previous Anthropic model we track is Claude Fable 5.1 (Sep 15, 2026), 7 days earlier.
Of the 60 models in our data with a published context window, Claude Opus 5.5 has the number 27 largest (1M tokens). Our data is not every model on the market.
Anthropic tools we cover: Claude Code, Claude.
All releases by date: AI model releases by month · new AI models this week. Choosing for code: best LLM for coding.

How Claude Opus 5.5 differs from Claude Opus 5

Read from the recorded facts of the two models, not from a head-to-head test. We have not run either.

Listed price is $4 in and $20 out, against $5 in and $25 out for Claude Opus 5 (per 1M tokens).
Both list a 1M-token context window.
Claude Opus 5.5 came out 60 days after Claude Opus 5.
Facts for the other model: Claude Opus 5.

What the sources say

These are claims from the linked pages, not our measurements.

Vendor claim (Anthropic newsroom): "leads in agentic coding and knowledge work, and costs 40% less to run than Opus 5 on typical workloads."
Anthropic's models overview says to start with Opus 5.5 for most workloads.

What we tested

Nothing yet. We have not run Claude Opus 5.5 ourselves, so every fact on this page is Reported from the sources below. When we do test it, the scope will be stated here and in our test logs. See methodology.