Claude Opus 5.5: what's new, what it costs and how it compares with Fable 5.1

Claude Opus 5.5 is Anthropic’s newest model and the first in its Claude 5.5 family, launched on September 22, 2026. Anthropic says it performs at the level of Claude Fable 5.1 on most work, at a lower price, and it is raising plan limits alongside the launch. This report covers what Anthropic announced about pricing, performance, safety and availability, and what it means for Claude subscribers.

Claude Opus 5.5 at a glance

What it costs

Anthropic says Opus 5.5 needs less compute to serve than Opus 5, and its pricing reflects that: $4 per million input tokens and $20 per million output tokens, 20% less than Opus 5, with cache reads at $0.20 per million tokens, 60% less. Anthropic’s tests show that at default settings it costs 40% less than Opus 5 on typical workloads, and it generates output more than 30% faster.

What changes for Pro, Max and Team subscribers

In addition to the price drop, Anthropic says it is increasing five-hour usage limits on Pro, Max, Team and seat-based Enterprise plans. Subscription users also get a rate limit reset that they can save and use whenever they choose. Anthropic’s announcement doesn’t give the new limits as numbers. Our guide to Claude Pro vs Max explains how the five-hour and weekly limits work.

What Anthropic says it can do

Anthropic describes Opus 5.5 as a major step up from Opus 5 and its new leading model. Its examples include a tester finishing a 680,000-line code migration in under a day, and a web-app optimisation test where Opus 5.5 succeeded 39 of 40 times at cutting page load times, while Opus 5 made smaller improvements that also changed the app’s behaviour. Early testers also said its writing is clearer, putting the most important information up front.

Anthropic’s own benchmark table, which reports vendor results, shows:

GPT-6 Astra scores slightly higher on AutomationBench in Anthropic’s own table, and Anthropic warns that at these levels benchmark margins are a less reliable guide to real-world differences, adding that in its own use the gap between Opus 5.5 and Fable 5.1 is narrower than the scores suggest. Treat vendor benchmarks as a starting point, and test on your own work.

Safety and access

Anthropic says Opus 5.5 is the strongest-performing model it has tested on its automated behavioural audit, is much less likely than recent models to take hard-to-reverse actions or act outside its boundaries, and is more resistant than Opus 5 to prompt injection. Because Opus 5.5 is comparable to Claude Mythos 5.1 in biology and cybersecurity, it ships with safeguards similar to Fable 5.1. Vetted organisations can apply to the Life Sciences Verification Program for biology research, and Anthropic says the Cyber Verification Program will expand access in the coming weeks.

Where Opus 5.5 fits

Anthropic’s model docs recommend starting with Opus 5.5 for most workloads, and using Claude Fable 5.1 for demanding reasoning and long-horizon agentic work or when Opus 5.5 at higher effort still falls short. Our guide to Claude models explained sets out the whole lineup, and for developers, see how to use Claude Code and the best AI coding assistants. The same week, OpenAI launched GPT-6 Sol and Luna, and on September 28 Anthropic followed with the cheaper Claude Sonnet 5.5. For the assistant overall, see the Claude profile.