The Pulse
Anthropic releases Claude Opus 5.5 at $4/$20, 20% below Opus 5
Anthropic's Claude Opus 5.5 costs $4/$20 per million tokens, 20% less than Opus 5, with cache reads down 60%. Anthropic rates it near Fable 5.1 on most work; it is generally available on Amazon Bedrock, Google Cloud and Microsoft Foundry.
AI.info Team ·
A cheaper Opus that Anthropic rates close to Fable 5.1
Anthropic released Claude Opus 5.5 on Tuesday, the first model in a new Claude 5.5 family. The company says it performs at the level of Claude Fable 5.1, its larger and more expensive model, on most work, and that at default settings it costs 40% less than Opus 5 to run on typical workloads.
The model went live the same day on the Claude Platform under the identifier claude-opus-5-5, and on Amazon Bedrock, Google Cloud and Microsoft Foundry. Anthropic also says Opus 5.5 generates output more than 30% faster than Opus 5.
Token prices down 20%, cache reads down 60%
Input and output tokens cost $4 and $20 per million, against $5 and $25 for Opus 5. Cache reads, which Anthropic says make up the majority of costs in agentic and coding work, fall from $0.50 to $0.20 per million tokens, and cache writes from $6.25 to $5.
Anthropic ties the cut to Opus 5.5 needing less compute to serve than its predecessor, and says the model also uses fewer tokens per task. A fast mode in Claude Code and on the Claude Platform runs at up to 2.5 times the speed for $8 per million input tokens and $40 per million output tokens. Pro, Max, Team and seat-based Enterprise subscribers get higher five-hour usage limits.
Benchmark leads that Anthropic itself discounts
In Anthropic's published table, Opus 5.5 scores 66.4% on Terminal-Bench 4.0, run at xhigh effort, against 55.8% for Fable 5.1 and 52.3% for Opus 5. On GDPval-AA v2.1, a test of professional work across 44 occupations, it reaches 1846 Elo at max effort, ahead of Fable 5.1 at 1735 and Opus 5 at 1708.
The company adds its own caveat: at these capability levels, benchmark margins have become "a less reliable guide to real-world differences," and in its own use the gap to Fable 5.1 is narrower than the scores suggest. The tests ran with production safeguards switched on; when those intervened, cybersecurity tasks were completed by Claude Opus 4.8 instead.
Early-access customers quoted by Anthropic mostly reported efficiency gains. GitHub tested the model in its Copilot tools:
“Developers want agents that can take on real software work and finish it. In our testing across GitHub Copilot CLI and VS Code, Claude Opus 5.5 used among the fewest tokens and steps we measured. In VS Code, it solved more terminal tasks than Opus 5 in less than half the steps. More than making individual tasks more efficient, it’s making developers’ bigger projects more achievable.”
Mario Rodriguez, Chief Product Officer, GitHub
Generally available on Bedrock, Google Cloud and Foundry
AWS says Opus 5.5 is available on Amazon Bedrock through US, EU, Australian, Japanese and global cross-region inference profiles, and in the US East (N. Virginia) and Asia Pacific (Melbourne) regions. It is also offered through Claude Platform on AWS in North America.
Google Cloud's model page lists Opus 5.5 as generally available with a release date of 22 September, up to 1,000,000 input tokens and 128,000 output tokens, and US and European multi-region plus global endpoints. Microsoft lists it in Foundry as generally available and hosted on Azure, in Global Standard and US DataZone deployments, at the same $4 and $20 rates, with a long-context variant priced identically.
Fable-class safeguards and a change for Opus 5 integrations
Opus 5.5 is the first Opus model to launch with a class of safeguards similar to Fable 5.1's for cybersecurity, biology and distillation. Anthropic says the model is comparable to Claude Mythos 5.1 in biology and cybersecurity, so most cybersecurity tasks will be re-routed to Opus 4.8. Vetted organisations can apply to a new Life Sciences Verification Program to use it for biology research.
The model also ships with preserved thinking, an anti-distillation measure that stops API users from editing Claude's prior context; it applies to API accounts created on or after 31 August 2026. External evaluators including METR and Frontier Design tested Opus 5.5 before release, and it is Anthropic's first model since the company called for pacing the frontier.
Developers moving from Opus 5 face breaking changes. Anthropic's documentation gives a 1M-token context window and 128K-token maximum output, and says thinking can no longer be disabled; its migration notes list further changes for code written against Opus 5.
Anthropic says Claude Sonnet 5.5 and Claude Haiku 5.5 will follow in the coming weeks, and that verified cybersecurity practitioners will gain access to Opus 5.5 through an expanded Cyber Verification Program over the same period.