Anthropic ships Claude Sonnet 5.5: 30%+ faster, up to 30% cheaper per task
Anthropic released Claude Sonnet 5.5 on September 28 as the second model in the Claude 5.5 family; priced like Sonnet 5 at $2/$10 per million tokens but up to 30% cheaper per task thanks to efficiency gains, scoring 70.6% on Terminal-Bench 4.0.
Anthropic released Claude Sonnet 5.5 on September 28, the second model in its Claude 5.5 family, six days after Opus 5.5 shipped on September 22. Anthropic says Sonnet 5.5 is more than 30 percent faster than Sonnet 5 and reduces task cost by up to 30 percent for most workloads, positioning it as the mid-tier workhorse of the 5.5 family for routine bug fixes, documents, slides, and spreadsheet tasks.
Pricing is unchanged from Sonnet 5: $2 per million input tokens, $10 per million output tokens, $0.20 per million cache reads. Anthropic stresses that list price is unchanged but efficiency gains mean fewer tokens and tool calls per task. On Terminal-Bench 4.0 Sonnet 5.5 scores 70.6 percent, far above the 10.3 percent reported for Sonnet 5. On the knowledge-work suite GDPval-AA v2.1 it scores 1844, essentially matching Opus 5.5 at 1846.
On safety, Sonnet 5.5 is the first Sonnet-tier model to ship with the network-security and anti-distillation safeguards from the Opus line. The model is available on the Claude platform and on AWS, Google Cloud, and Microsoft Azure; the API model name is claude-sonnet-5-5. Anthropic says Claude Haiku 5.5 will join the 5.5 family in the coming weeks. On the same day, Claude Code 2.1.284 switched its default model to Sonnet 5.5 and started showing cost in dollars in the terminal.