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Claude Fable 5.1

Anthropic

The highest measured reasoning score we track.

Best reasoning

Ranked #5 of 402 on LMArena’s overall board (style control) · retrieved 2026-09-19

The numbers

Arena Score (LMArena, style control)1498.5 (1490.3–1506.6, 5,783 votes)
Coding board score1518.9 (#32, 1,184 votes)
Intelligence Index (Artificial Analysis)53.4
Median output speed~69 tokens/sec
Price per 1M tokens in/out (LMArena)$10 / $50
Context window~1M
LicenseProprietary
Released2026-09-01

Exact source entries: LMArena “claude-fable-5.1-max” · Artificial Analysis “Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback)”, retrieved 2026-09-19.

Try or learn more

Honest read

Best at

  • Artificial Analysis Intelligence Index 53.4 — the best number we recorded on 2026-09-20
  • #5 overall on LMArena (1498) with 5,783 votes
  • 1,000,000-token context window

Not the pick for

  • Same premium price as Fable 5 ($10 / $50) while ranking slightly lower on overall human preference
  • Max-effort modes burn reasoning tokens — watch your bill

Choose it if you are

Hard analysis, mathematics and long planning chains where pure reasoning depth is the point.

Rankings come from the sources above; this plain-language read is our editorial summary of those numbers.

Compare with the leaders

Best image Text-to-image, by blind human votes GPT-Image 2.5 (Sunburst) · Arena Score 1421 Best video Text-to-video, by blind human votes Gemini Omni 1.1 Flash · Arena Score 1515 Best code Coding, by blind human votes Claude Fable 5 · Arena Score 1552 Best open model Open weights, by human votes Kimi K3 · Arena Score 1485 Best value Intelligence per dollar GLM 5.3 Flash · 176 pts / $1M