Claude Fable 5.1 takes the top of the lineup, and Fable 5 moves to legacy
The current lineup on Anthropic's own comparison table is now Claude Fable 5.1, Claude Opus 5, Claude Sonnet 5 and Claude Haiku 4.5[1]. Claude Fable 5 has moved to the list of legacy models, which are still available[1].
Fable 5.1 holds 1 million tokens of context and 128K of output in one response, the same as Fable 5, Opus 5 and Sonnet 5[1]. The price is unchanged too, at $10 input and $50 output per million tokens[1,2].
What moved is the knowledge cutoff and the retirement date. The reliable knowledge cutoff is June 2026, against January 2026 on Fable 5, and the training data cutoff is the same June 2026[1]. The retirement commitment is not sooner than 1 September 2027, where Fable 5 sits at 9 June 2027[1].
Thinking is adaptive and always on, and the default effort is high[1]. Anthropic's own advice is to start with Opus 5 for most work, and to reach for Fable 5.1 for demanding reasoning and long-horizon agentic work, or when evals on Opus 5 at a higher effort still fall short[1].
Claude Mythos 5.1 carries the same prices and sits alongside it, at limited availability[2].