- Start
- Sep 22, 202690% CONFIDENCEfrom the source
Claude Opus 5.5 Released
- Input and output tokens fall to $4 and $20 per million, "20% less than Opus 5" - TechCrunch and XDA give the old prices as $5 and $25 - and cache reads drop to $0.20 per million, 60% less; output also generates "more than 30% faster"[1][3][4]
- It is "our first release since we called for pacing the frontier" and was tested before release by external evaluators including Frontier Design and METR; on Anthropic's automated behavioral audit it is "the strongest-performing model we've tested to date"[1]
- Because it is "comparable to Claude Mythos 5.1 in biology and cybersecurity" it ships with safeguards like Claude Fable 5.1's, plus EU AI Act watermarking, and it is no longer available with thinking mode switched off[1]
- One early tester "completed a 680,000-line code migration in less than a day"; asked to cut load times across every page of a web app, Opus 5.5 "succeeded 39 of 40 times" where Opus 5 made smaller changes that also altered the app's behaviour[1]
- Available the same day on Amazon Web Services, Google Cloud and Microsoft Azure, and as
claude-opus-5-5on the Claude Platform; Claude Sonnet 5.5 and Claude Haiku 5.5 "will follow in the coming weeks"[1]
Notable features
- Anthropic introduces Claude Opus 5.5, "the first model in our new Claude 5.5 family", which "performs at the level of Claude Fable 5.1 on most work and costs 40% less to run than Opus 5"[1][3]
- Specifications: 1M-token context window, 128K max output tokens (300K on the Batch API in beta), adaptive thinking that is always on with medium default effort, text and image input with text output, and a June 2026 reliable knowledge cutoff[2]
- It leads Anthropic's benchmark table in agentic coding, computer use and knowledge work: Terminal-Bench 4.0 66.4% against Fable 5.1's 55.8%, Opus 5's 52.3% and GPT-6 Astra's 57.9%; GDPval-AA v2.1 1846 against 1735, 1708 and 1542[1]
- Anthropic cautions that "at these levels of capability we've found that benchmark margins have become a less reliable guide to real-world differences", and that in its own use "the gap between Opus 5.5 and Claude Fable 5.1 is narrower than these scores suggest"[1]
- TechCrunch notes the release "makes significant changes to how Opus communicates" - less jargon, important information first - which Anthropic frames as a safety benefit as well as a practical one[1][3]
References 490% CONFIDENCE
The first entry is always the pin's source. Overall confidence is a weighted average of how firmly each reference supports the start and end times used above; a reference counts half as much for every 180 days older than the newest.
- [1]95%Introducing Claude Opus 5.5anthropic.com· Published Sep 22, 2026· Starts Sep 22, 2026 ✓· 25% of score
Unlike the Fable 5.1 announcement, this page dates itself: the header reads “Claude[2] Opus 5.5 September 22, 2026”. TechCrunch's[3] byline (“9:30 AM PDT · September 22, 2026”, “released on Tuesday”) and XDA's 2026-09-22T16:44Z timestamp agree, so the source keeps the claim and the two reports corroborate it.
- [2]90%Claude Opus 5.5 - Claude Platform Docsplatform.claude.com· Added Sep 22, 2026· 25% of score
Anthropic's[1] Claude Opus 5.5 model page lists a 1M-token context window, 128K max output (300K Batch beta), adaptive thinking always on with medium default effort, and a Jun 2026 knowledge cutoff.
- [3]90%Anthropic releases Opus 5.5 with lower prices and Fable-level performancetechcrunch.com· Published Sep 22, 2026· Starts Sep 22, 2026· 25% of score
TechCrunch's same-day report by Russell Brandom, bylined “9:30 AM PDT · September 22, 2026” and saying the model “was released on Tuesday”. It supplies the Opus 5 comparison prices ($25 per million output tokens) that the announcement states only as a percentage.
- [4]85%Anthropic releases Claude Opus 5.5, and it's not just more powerful: it's cheaper, tooxda-developers.com· Published Sep 22, 2026· Starts Sep 22, 2026· 25% of score
XDA's report, timestamped 2026-09-22T16:44Z, independently confirms the launch day and gives both old prices in full - “Claude[2] Opus 5 costs $5 for 1 million input tokens and $25 for 1 million output tokens” against $4 and $20.
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