In this guide
What Anthropic announced
Anthropic released Claude Sonnet 5.5 on September 28, 2026 across its platform, AWS, Google Cloud, and Microsoft Azure. It reports output more than 30% faster than Sonnet 5 and up to 30% lower cost per task, while API list prices remain $2 per million input tokens, $10 per million output tokens, and $0.20 per million cache-read tokens.
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Price per token is not price per outcome
A model can keep the same token price and still lower completed-task cost by using fewer tokens, finishing with fewer retries, or reducing human correction. It can also cost more if stronger capabilities encourage longer tasks, more tools, higher effort, or broader autonomy. Measure accepted outcomes, not a vendor percentage.
Treat benchmarks as directional
Anthropic reports large gains on Terminal-Bench and near-Opus performance on knowledge-work evaluations. Those are useful signals, not guarantees for a buyer's repository, documents, tool permissions, or acceptance criteria. The announcement also notes benchmark configuration and pre-release deployment caveats.
Migration details matter
Teams using thinking-off behavior must review the new between-tools setting. Pin the model identifier, replay tool calls, structured outputs, long contexts, image tasks, refusals, and failure recovery. Keep a rollback path until the new version passes production-shaped tests.
Bottom line
Sonnet 5.5 looks promising for well-scoped everyday and coding work. Adopt it when representative replays show lower cost per approved result without new correctness, safety, or tool-use regressions.
Transparency
How this guide was checked
About this article
How this article was prepared
- Evaluation type
- Source-based research
- Last reviewed
- Evidence
- 4 listed sources
We label hands-on testing separately. Research-based articles draw on product documentation and other cited sources, rather than direct use of every plan. Read the full methodology.
Editorial basis
Sources and testing
- Editorial basis
- Source-based research
- Primary references
- 4
- Products covered
- 1
- Last checked
- 2026-09-30
Important limits
- • Performance and savings claims are primarily vendor-reported.
- • No independent production benchmark was conducted by DiscoverAI.
Sources and references
References cited by this article. Check the original source for scope, dates and current terms.
Frequently asked questions
How much does Claude Sonnet 5.5 cost?
Anthropic lists $2 per million input tokens, $10 per million output tokens, and $0.20 per million cache-read tokens; platform and provider terms can differ.
Why can cost per task fall if token prices stay the same?
A task can require fewer tokens, retries, or corrections. Only a replay of representative work can establish that saving.
Is Sonnet 5.5 available now?
Anthropic says it is available on the Claude Platform and through AWS, Google Cloud, and Microsoft Azure.
Should teams migrate immediately?
No broad switch is necessary. Pin versions, replay real workloads, validate tool and thinking behavior, and retain rollback before changing production traffic.
Tools mentioned in this article
Claude
Anthropic's thoughtful, safety-focused AI with exceptional long-form reasoning
Claude excels at deep analysis, long-form writing, and nuanced reasoning. Built by Anthropic with a focus on safety and helpfulness.
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