News · Claude
Claude introduces Sonnet 5.5, emphasizing improved speed and efficiency
Posted on X by Claude (@claudeai) on 28 September 2026. The headline is our summary; the post itself is quoted below.
Claude@claudeai ·
Introducing Claude Sonnet 5.5, the second model in the Claude 5.5 family. It’s a clear upgrade over Sonnet 5, runs more than 30% faster, and…
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Context
- Claude Code 2.1.284Released the same day (UTC). Added Claude Sonnet 5.5 (claude-sonnet-5-5), now the default Sonnet model on the Anthropic API — 1M context, $2/$10 per Mtok with $0.20/Mtok cache reads…
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