SIRumors
ReleasedSep 28, 2026 ·

Claude Sonnet 5.5 is out

Anthropic shipped Claude Sonnet 5.5.

Anthropic

Anthropic released Claude Sonnet 5.5 on Sep 28, 2026. The company announced it itself (Claude on X).

It follows Claude Sonnet 5, 90 days earlier. Releases in the Claude Sonnet line usually land about 130 days apart.

Based on that pace, the next Claude Sonnet release is expected around Feb 5, 2027. That is our estimate, not a leak.

“Introducing Claude Sonnet 5.5, the second model in the Claude 5.5 family.”
Claude on X
Released
Sep 28, 2026
Line
Claude Sonnet
Previous
Claude Sonnet 5 (Jun 30, 2026)
Confirmed by
The company's own announcement

Source: Claude on X

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