AI/News
Anthropic releases Claude Sonnet 5.5 at Sonnet 5's price
Same per-token price; the 'up to 30% less' is per task in Anthropic's own testing, because it uses fewer tokens.
By Daily Aletheia · Checked against the primary source · 29 September 2026 · 2 min read
Anthropic released Claude Sonnet 5.5 on 28 September, the second model in its 5.5 family after Opus 5.5. Haiku 5.5 is due "in the coming weeks".
What the page says
Pricing is unchanged from Sonnet 5: $2 per million input tokens, $10 per million output, $0.20 per million for cache reads. The saving Anthropic claims comes from the model needing fewer tokens: "up to 30% less per task" in its own testing. It says output is generated 30%+ faster.
On Terminal-Bench 4.0, an agentic coding test, it scores 70.6% against Sonnet 5's 10.3% and Opus 5.5's 66.4%. On OSWorld 2.1, for computer use, it scores 80.1% against Opus 5.5's 81.8%. On GDPval-AA, a test of real-world work across 44 occupations, it sits two points below Opus 5.5.
Anthropic still says Opus 5.5 "remains clearly stronger at complex, open-ended work requiring sustained judgment".
Safeguards
Because its cyber capability is comparable to Opus 5's, it is the first Sonnet to ship with the cyber safeguards used on Anthropic's top models: higher-risk security tasks "visibly fall back to Sonnet 5". It also ships with classifiers against distillation, the practice of extracting a model's abilities through thousands of fake accounts.
It is available now on Anthropic's platform, AWS, Google Cloud and Microsoft Azure as claude-sonnet-5-5. Developers who run Sonnet with thinking off must switch to a new setting before moving over.