Claude Fable 5.1

• Joint first on the re-based Artificial Analysis Intelligence Index v4.3 (53, level with GPT-6 Astra), first on the official Terminal-Bench v4.0 board at 57.9%, and first on Vellum's quality/speed/cost composite at 65%.
• On Arena text it sits at 1504 inside a 1-6 tie band with the rest of the Anthropic top group.
• Costs more per Index task than GPT-6 Astra ($7.63 against $3.26), so price the alternative if volume matters.

• artificialanalysis.ai/models
• x.com/kimmonismus/status/2116845494454350227
• deepmind.google/blog/gemini-4-carbon-our-next-frontier-model/
• www.anthropic.com/claude/fable
• lmarena.ai/leaderboard
• www.vellum.ai/llm-leaderboard
• www.tbench.ai/leaderboard
• openai.com/index/gpt-6-astra

Vendor numbers are treated as claims until independently reproduced — how we judge. Structured benchmark comparisons are on the roadmap.

• Artificial Analysis has re-based again: the live board is Intelligence Index v5, where Gemini 4 Carbon (high) leads on 59, Claude Opus 5.5 (max) is on 58 and GPT-6 Astra (max) on 57, while Claude Fable 5.1 reads 50 (xhigh, $10.85 per task) and 49 (max, $12.99) — so the v4.3 score of 53 and the $7.63 against $3.26 comparison no longer apply.
• On Terminal-Bench 4.0 the 57.9% figure is a Claude Code max-effort row on the official board, which runs each vendor in its own agent and so cannot rank vendors against each other; Vals AI's neutral mini-SWE-agent run puts Claude Opus 5.5 first at 65.15%, with Anthropic quoting 66.4% itself.
• Arena has moved on too: its published 28 October board has Gemini 4 Carbon and Claude Opus 5.5 at the top with Fable 5.1 fourth overall, so ignore the 2 September 1507/1504 snapshot and read the live board.

Title

Best overall LLM

Licence

proprietary

Pick since

10 Sep 2026

Last reviewed

1 Nov 2026

Title holders to date

10

Official page

www.anthropic.com/claude/fable