Breaking

Anthropic Claude Fable 5.1 Faces Multi-Model Quality-Versus-Price Tests After Launch

September 2, 2026 at 17:42 EDT

Foundation Models
Software Dev & Coding

Anthropic’s Claude Fable 5.1, generally available as of September 1, 2026, is being compared with Claude Fable 5, Claude Opus 5, GPT-5.6, Kimi K3, GLM 5.3, Qwen-3.8, Grok-4.6, and DeepSeek on coding, 3D, SVG, research, and data-visualization work, with per-generation costs reported from cents to more than $65. The comparison, run by Arena researcher Peter Gostev, asks whether the new model is actually better once quality is weighed against price rather than vendor leaderboards alone.

September 1, 2026 · Anthropic

Fable 5.1 vs the field on quality and price

Claude Fable 5.1 is generally available. Independent testers are stacking it against Fable 5, Opus 5, GPT-5.6, Kimi K3, GLM 5.3, Qwen-3.8, Grok-4.6, and DeepSeek on coding, 3D, SVG, research, and data viz, with generations from cents to $65+.

Terminal-Bench-Science 0.1 (accuracy)

52.6%

Fable 5.1

29.0%

Opus 5

24.7%

Fable 5

22.4%

GPT-5.6 Sol

Fable 5.1 more than doubles Fable 5 on this science-agent test.

$10 / $50

Fable 5.1 list per 1M tokens

$5 / $25

Opus 5 list (half the sticker)

−75%

Cache reads now $0.25 / 1M

$3.76

AA Index task vs $2.34 Opus 5

AA Intelligence Index cost per task (max effort)

$2.34

Opus 5 · 63

$3.76

Fable 5.1 · 66

Three Index points more, at a higher per-task cost than Opus 5.

Where it helps

Faster, cheaper successful coding runs (58% fewer output tokens, 36% faster). Stronger iterative app fixes in some product tests.

Where it is not automatic

Opus 5 still leads matched pass@1 and solves more tasks at least once. Anthropic still says start with Opus 5.

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