Anthropic releases Claude Sonnet 4.6
Claude Sonnet 4.6 (`claude-sonnet-4-6`) was released on February 17, 2026 with a 1M-token context and 128K output. It stayed the default Free/Pro model until Sonnet 5 replaced it on July 1, 2026.
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.
Changelog
- 2026-09-29: created
Related events
- Anthropic releases Claude Opus 4.6 with 1M context, adaptive thinking and agent teams ★★★
- Anthropic releases Claude Sonnet 5, "the most agentic Sonnet yet" ★★★
Sources (2)
- discussionAnthropic Claude model release timeline (hidekazu-konishi.com)
- discussionEverything Anthropic shipped in 2026 (Linas Substack)
id: 2026-02-17-claude-sonnet-4-6 · updated 2026-09-29 · open in the interactive timeline