Anthropic · llm model

Claude Sonnet 5.5

Claude Sonnet 5.5 is an Anthropic language model released Sep 28, 2026; Anthropic's newest language model in our dataset is Claude Haiku 5.5. Proprietary, API access only. The mid-priced Claude model: Anthropic says it runs 30%+ faster than Sonnet 5 and costs up to 30% less for most work. Verified against vendor sources on Oct 26, 2026.

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

ReleasedSep 28, 2026
Context window1M1,000,000 tokens
LicenceProprietaryProprietary (API)

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Key facts

Claude Sonnet 5.5: key facts with sources
Fact	Value	Source
Vendor	Anthropic	n/a
Released	Sep 28, 2026 Anthropic's newsroom date. At least one third-party site gives Oct 1; we use the vendor's date.	source
Status	generally available	n/a
API id	claude-sonnet-5-5	source
Context window	1,000,000 tokens (1M)	source
Input	text, image	source
Output	text	source
Licence	Proprietary (API)	source
Pricing	$2 in / $10 out per 1M tokens	source

Where Claude Sonnet 5.5 sits in our data

Released Sep 28, 2026 (week 40 of 2026), in September 2026. Other models in our data released that month: GPT-6.1 Sol, Claude Opus 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 Opus 5.5 (Sep 22, 2026), 6 days earlier.
Of the 60 models in our data with a published context window, Claude Sonnet 5.5 has the number 26 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 Sonnet 5.5 differs from Claude Sonnet 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 the same as Claude Sonnet 5: $2 in and $10 out (per 1M tokens).
Both list a 1M-token context window.
Claude Sonnet 5.5 came out 90 days after Claude Sonnet 5.
Facts for the other model: Claude Sonnet 5.

What we tested

Nothing yet. We have not run Claude Sonnet 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.

Not verified, left out

We could not confirm these on a vendor page, so we do not state them.

Maximum output tokens for Sonnet 5.5 were not captured.