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Anthropic · model passport

Anthropic: Claude Fable 5.1

claude-fable-5-1
  • Cloud only
  • Proprietary licence
  • 1,000,000 context
  • Released 2026-09-13(first seen on LMArena)
14/27axes covered
Overall · LMArena
1,502#6 of 396
Best percentile
100.0AIME (math)
Cohort standing
88.0median 60.4

What the data says

Benchmarked on 14 of 27 tracked axes. Every figure below is the model's own published result on that board.

Strongest axes

  • 100 pct — AIME (math) (100.0%)
  • 98.8 pct — Factuality Arena (1,498)
  • 98.7 pct — Overall (1,502)

Uneven: 9.3 percentile points between its best and worst axis — 100 pct on AIME (math) versus 90.7 pct on Vision Arena.

  • AIME (math)100 pct100.0%Verify →
  • Factuality Arena98.8 pct1,498Verify →
  • Overall98.7 pct1,502Verify →
  • Instruction following98.7 pct1,499Verify →
  • Hard prompts98.5 pct1,521Verify →
  • Humanity's Last Exam97.8 pct46.5%Verify →
  • Coding97.2 pct1,537Verify →
  • WebDev Arena97.1 pct1,743Verify →
  • Agent Arena94.5 pct0.140Verify →
  • ARC-AGI-294.4 pct90.0%Verify →
  • SimpleQA Verified93.9 pct70.8%Verify →
  • Search Arena92.9 pct1,233Verify →
  • Document Arena92.1 pct1,493Verify →
  • Vision Arena90.7 pct1,286Verify →
  • GPQA DiamondNot benchmarked
  • FrontierMathNot benchmarked
  • SimpleBenchNot benchmarked
  • LiveBenchNot benchmarked
  • BFCL v4 (function calling)Not benchmarked
  • SWE-bench Verified (live board)Not benchmarked
  • Terminal-Bench 4.0Not benchmarked
  • MMLU-Pro (Artificial Analysis)Not benchmarked
  • LiveCodeBench (Artificial Analysis)Not benchmarked
  • IFBench (Artificial Analysis)Not benchmarked
  • HHEM Hallucination (Vectara)Not benchmarked
  • SWE-bench VerifiedNot benchmarked
  • Terminal-BenchNot benchmarked

Percentiles are the model's standing within each board's own population. Axes marked "not benchmarked" have no published result for this model — that is an absence of data, not a low score.

How to run it

Use it hosted

API model IDanthropic/claude-fable-5.1
Context length1,000,000 tokens
Max output128,000 tokens
Acceptstext, image, file
Input price$10 per 1M tokens
Cached input price$0.25 per 1M tokens
Output price$50 per 1M tokens

API parameters this endpoint supports

Include reasoningMax completion tokensMax tokensReasoningReasoning effortResponse formatStop sequencesStructured outputsTool choiceTool callingVerbosity

Example request

curl https://openrouter.ai/api/v1/chat/completions \
  -H "Authorization: Bearer $OPENROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"anthropic/claude-fable-5.1","messages":[{"role":"user","content":"Hello"}]}'

View on OpenRouter →

Identifiers, limits and prices are synced from the upstream source shown above. Any field we haven't synced is left out entirely rather than guessed.

  • Claude Fable 5.1 (Max) stands at 88 (raw mean 96.1) — measured on 14 of 27 axes.

    standingtemplateVerify →

  • Claude Fable 5.1 (Max) stands at 88 versus a cohort median of 60.4 across 175 models released within 180 days — above the peer median.

    cohorttemplateVerify →

Every claim is a computed fact from the current board data, phrased by a low-temperature model call and rejected by a validation gate if any number is not in the source row. How the leaderboards work →