Anthropic releases Claude Sonnet 4.6
Partly confirmed
The takeaway
Claude Sonnet 4.6 (claude-sonnet-4-6) was released on February 17, 2026 with a 1M-token context and 128K output.
Status
- Claim
Partly confirmed
- Our reporting
- Medium confidence
- Importance
- 2 of 5
- Last verified
- 29 September 2026
Your AI and this story
- GPT-6 AstraIn its training data
- Claude Opus 5.5In its training data
- Gemini 4 HydrogenIn its training data
- Grok 4.7In its training data
It happened before the cutoffs of all four assistants, so it can be in their training data.
Key facts
- Released February 17, 2026; model id claude-sonnet-4-6; 1M context, 128K output (third-party timeline)
- Replaced as Free/Pro default by Sonnet 5 on July 1, 2026
What happened
A mid-tier update following Opus 4.6. The details here come from third-party timelines; the official announcement was not fetched.
Why it matters
It was the workhorse default model for most Claude users in the first half of 2026.
Sources
2 sources from 2 sites. Numbers match the chips in the text.
2 sources: 2 reactions
Reactions
- Anthropic Claude model release timeline (hidekazu-konishi.com)hidekazu-konishi.com, discussion
- Everything Anthropic shipped in 2026 (Linas Substack)linas.substack.com, discussion
Changes
- Filed