Claude Fable 5.1 vs Muse Spark 1.3

  • Claude Fable 5.1 rates higher on LMArena’s text leaderboard: 1513 against 1491.
  • Muse Spark 1.3 is cheaper: $1.25 / $4.25 per million input / output tokens, against $10 / $50 for Claude Fable 5.1.
  • On the 5 Vals AI benchmarks both have taken, Claude Fable 5.1 wins 5 and Muse Spark 1.3 wins 0.

Side by side

Models (2/6)
  • Claude Fable 5.1
  • Muse Spark 1.3
BenchmarkClaude Fable 5.1Muse Spark 1.3
The model
LabAnthropicMeta
Released2026-09-012026-09-02
WeightsProprietaryProprietary
Context window1M1M
Input, per 1M tokens$10$1.25
Output, per 1M tokens$50$4.25
LMArena, people’s votes
LMArena TextMillions of people compare two anonymous models side by side and vote for the better answer1513#3 of 3511491#10 of 351
LMArena WebDevPeople ask two anonymous models to build the same web app, try both and vote for the better one1743#5 of 1241657#16 of 124
LMArena VisionSide-by-side votes on prompts that include an image1320#4 of 1461308#12 of 146
LMArena CodingLMArena’s text votes on prompts that ask for code1531#7 of 3461511#13 of 346
LMArena MathLMArena’s text votes on math prompts1532#3 of 3391502#13 of 339
LMArena Creative writingLMArena’s text votes on stories, poems and other creative writing1510#3 of 3491462#23 of 349
LMArena Hard promptsLMArena’s text votes on the hardest prompts1528#3 of 3511504#13 of 351
LMArena Instruction followingLMArena’s text votes on prompts with specific instructions to follow1519#4 of 3511479#21 of 351
Vals AI, coding
Terminal-Bench 4.0Frontier-difficulty tasks an agent completes in a real terminal58.08%#5 of 5510.61%#41 of 55
Vibe Code BenchBuilding complete web apps from a plain-language brief, graded on whether the app works90.26%#6 of 11582.86%#21 of 115
LiveCodeBenchFresh competitive programming problems, collected after models’ training cut-offs to avoid contamination90.52%#1 of 143—
Vals AI, finance
Tax Agent BenchAgentic research into US corporate tax questions49.19%#2 of 7635.97%#13 of 76
Vals AI, law
Legal Research BenchAgentic US legal research55.29%#3 of 8540.87%#29 of 85
Vals AI, medicine
MedCodeAssigning the right medical billing codes from clinical notes53.51%#8 of 107—
Vals AI, reasoning
GPQA DiamondGraduate-level questions in biology, physics and chemistry that experts answer well and search does not93.43%#9 of 138—
MMLU-ProHarder, reasoning-focused multiple choice across 14 subjects, from law to engineering92.38%#1 of 138—
MMMUCollege-level questions that need both an image and text90.64%#1 of 93—
Terminal-Bench ScienceExpert-written scientific research workflows, run by an agent in a terminal40.00%#6 of 424.29%#25 of 42

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Questions

Which is better, Claude Fable 5.1 or Muse Spark 1.3?

Claude Fable 5.1 rates higher on LMArena’s text leaderboard: 1513 against 1491. Muse Spark 1.3 is cheaper: $1.25 / $4.25 per million input / output tokens, against $10 / $50 for Claude Fable 5.1. On the 5 Vals AI benchmarks both have taken, Claude Fable 5.1 wins 5 and Muse Spark 1.3 wins 0.

Which is cheaper, Claude Fable 5.1 or Muse Spark 1.3?

Muse Spark 1.3 is cheaper: $1.25 / $4.25 per million input / output tokens, against $10 / $50 for Claude Fable 5.1.

Sources

Every number on this page comes from these sources; models without a published number show none. Download the data. Cite as “Nexus Explorer, nexus.inc/models”.