Claude Opus 5 vs Muse Spark 1.3

  • Claude Opus 5 rates higher on LMArena’s text leaderboard: 1508 against 1491.
  • Muse Spark 1.3 is cheaper: $1.25 / $4.25 per million input / output tokens, against $5 / $25 for Claude Opus 5.
  • On the 5 Vals AI benchmarks both have taken, Claude Opus 5 wins 5 and Muse Spark 1.3 wins 0.

Side by side

Models (2/6)
  • Claude Opus 5
  • Muse Spark 1.3
BenchmarkClaude Opus 5Muse Spark 1.3
The model
LabAnthropicMeta
Released2026-07-242026-09-02
WeightsProprietaryProprietary
Context window1M1M
Input, per 1M tokens$5$1.25
Output, per 1M tokens$25$4.25
LMArena, people’s votes
LMArena TextMillions of people compare two anonymous models side by side and vote for the better answer1508#4 of 3511491#10 of 351
LMArena WebDevPeople ask two anonymous models to build the same web app, try both and vote for the better one1691#9 of 1241657#16 of 124
LMArena VisionSide-by-side votes on prompts that include an image1320#3 of 1461308#12 of 146
LMArena CodingLMArena’s text votes on prompts that ask for code1533#4 of 3461511#13 of 346
LMArena MathLMArena’s text votes on math prompts1533#2 of 3391502#13 of 339
LMArena Creative writingLMArena’s text votes on stories, poems and other creative writing1495#5 of 3491462#23 of 349
LMArena Hard promptsLMArena’s text votes on the hardest prompts1527#4 of 3511504#13 of 351
LMArena Instruction followingLMArena’s text votes on prompts with specific instructions to follow1518#5 of 3511479#21 of 351
Vals AI, coding
Terminal-Bench 4.0Frontier-difficulty tasks an agent completes in a real terminal53.53%#9 of 5510.61%#41 of 55
SWE-benchReal GitHub issues from open-source projects97.00%#1 of 85—
Vibe Code BenchBuilding complete web apps from a plain-language brief, graded on whether the app works88.40%#9 of 11582.86%#21 of 115
LiveCodeBenchFresh competitive programming problems, collected after models’ training cut-offs to avoid contamination89.03%#4 of 143—
Vals AI, finance
Tax Agent BenchAgentic research into US corporate tax questions45.55%#4 of 7635.97%#13 of 76
Vals AI, law
Legal Research BenchAgentic US legal research55.29%#2 of 8540.87%#29 of 85
Vals AI, medicine
MedCodeAssigning the right medical billing codes from clinical notes63.57%#1 of 107—
Vals AI, reasoning
GPQA DiamondGraduate-level questions in biology, physics and chemistry that experts answer well and search does not93.43%#8 of 138—
MMLU-ProHarder, reasoning-focused multiple choice across 14 subjects, from law to engineering91.59%#2 of 138—
MMMUCollege-level questions that need both an image and text89.88%#2 of 93—
Terminal-Bench ScienceExpert-written scientific research workflows, run by an agent in a terminal27.14%#9 of 424.29%#25 of 42

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Questions

Which is better, Claude Opus 5 or Muse Spark 1.3?

Claude Opus 5 rates higher on LMArena’s text leaderboard: 1508 against 1491. Muse Spark 1.3 is cheaper: $1.25 / $4.25 per million input / output tokens, against $5 / $25 for Claude Opus 5. On the 5 Vals AI benchmarks both have taken, Claude Opus 5 wins 5 and Muse Spark 1.3 wins 0.

Which is cheaper, Claude Opus 5 or Muse Spark 1.3?

Muse Spark 1.3 is cheaper: $1.25 / $4.25 per million input / output tokens, against $5 / $25 for Claude Opus 5.

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”.