Noometry

Model comparison

Claude Opus 5 vs Grok 4 Fast

Claude Opus 5 is the stronger model overall, scoring 67.8 to 39.4 on the Noometry Index.

Last verified . 24 shared benchmarks.

Claude Opus 5 Anthropic

67.8

Rank #4 Confirmed

Grok 4 Fast xAI

39.4

Rank #167 Confirmed

Summary

  • They share 24 benchmarks with published results for both. Claude Opus 5 scores higher in 8 categories and Grok 4 Fast in 1 category; 9 gaps are clear of the uncertainty.
  • The widest gap is in reasoning, where Claude Opus 5 leads 77.2 to 22.2.
  • The biggest single-benchmark swing is ARC-AGI-2: 90.4% for Claude Opus 5 and 5.3% for Grok 4 Fast.

Side by side

Claude Opus 5Grok 4 Fast
ProviderAnthropicxAI
Noometry Index67.839.4
Released2026-07-242025-09-19
WeightsProprietaryProprietary
Context window1M—
Max output128K—
Input $ / M tokens$5—
Output $ / M tokens$25—
Results tracked5730

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Category by category

Coding Claude Opus 5 leads

Claude Opus 5: 67.5 (#5), Grok 4 Fast: 32.5 (#271)

BenchmarkClaude Opus 5Grok 4 Fast
LMArena WebDev16911159
WeirdML91.8%42.9%
LMArena Coding15341429
DeepSWE73.6%—
FrontierCode53.4%—
CursorBench46.6%—
FrontierSWE52%—
SciCode56.4%—
ALE-Bench2,165—

Agentic & Tool Use Claude Opus 5 leads

Claude Opus 5: 55.6 (#1), Grok 4 Fast: 29.5 (#86)

BenchmarkClaude Opus 5Grok 4 Fast
τ²-bench Banking48.7%15.7%
APEX-Agents65.8%—
OSWorld 2.031.4%—
Cybench—30%
PostTrainBench35%—
BALROG63.4%—
GBAEval79.6%—
GDP.pdf24%—
LMArena Search—1171
Vending-Bench 211,182—

Reasoning Claude Opus 5 leads

Claude Opus 5: 77.2 (#4), Grok 4 Fast: 22.2 (#201)

BenchmarkClaude Opus 5Grok 4 Fast
ARC-AGI-290.4%5.3%
ARC-AGI-197.5%48.5%
LMArena Hard Prompts15261412
DTBench97.9%82.7%
Epoch Capabilities Index162.78144.2
SimpleBench80.6%—
Kagi LLM Benchmark—66.1%
NYT Connections (extended)94.3%—
CritPt29.1%—
Chess Puzzles42%—
EBR-Bench45.7%—
Mystery Game Puzzles59%—
LMCA64.5%—
Bench to the Future 30.12—
ForecastBench—60.5

Math Claude Opus 5 leads

Claude Opus 5: 86.2 (#8), Grok 4 Fast: 38.9 (#123)

BenchmarkClaude Opus 5Grok 4 Fast
LMArena Math15311419
FrontierMath (Tiers 1-3)85.6%—
FrontierMath Tier 473.2%—
OTIS Mock AIME 2024-202598.9%—
ProofBench99%—

Knowledge Claude Opus 5 leads

Claude Opus 5: 66.8 (#9), Grok 4 Fast: 32.0 (#214)

BenchmarkClaude Opus 5Grok 4 Fast
LMArena Expert15571411
GPQA Diamond93.9%—
SimpleQA Verified59.9%—
Vectara Hallucination Rate—19.7%

Multimodal Not comparable

Claude Opus 5: 50.8 (#8), Grok 4 Fast: —

BenchmarkClaude Opus 5Grok 4 Fast
LMArena Vision1319—
Blueprint-Bench 230.4%—
Furniture Assembly60.8%—
LMArena Document1516—

Multilingual Claude Opus 5 leads

Claude Opus 5: 58.8 (#4), Grok 4 Fast: 51.3 (#111)

BenchmarkClaude Opus 5Grok 4 Fast
LMArena Non-English15011396
LMArena Chinese15741457
LMArena French15191431
LMArena German15241383
LMArena Japanese15161352
LMArena Korean15211357
LMArena Russian15071389
LMArena Spanish15191415

Instruction Following Claude Opus 5 leads

Claude Opus 5: 79.2 (#7), Grok 4 Fast: 73.2 (#121)

BenchmarkClaude Opus 5Grok 4 Fast
LMArena Instruction Following15171387

Long Context Grok 4 Fast leads

Claude Opus 5: 46.5 (#21), Grok 4 Fast: 63.2 (#3)

BenchmarkClaude Opus 5Grok 4 Fast
LMArena Longer Query15151415
Fiction.LiveBench—94.4%

Writing & Preference Claude Opus 5 leads

Claude Opus 5: 79.2 (#1), Grok 4 Fast: 60.0 (#102)

BenchmarkClaude Opus 5Grok 4 Fast
LMArena Text15071407
LMArena Creative Writing14911387
LMArena Multi-Turn14991414
EQ-Bench Creative Writing2133—
EQ-Bench 41385—

Frequently asked questions

Is Claude Opus 5 better than Grok 4 Fast?

Claude Opus 5 is the stronger model overall, scoring 67.8 to 39.4 on the Noometry Index.

Is Claude Opus 5 or Grok 4 Fast better for coding?

Claude Opus 5 scores higher on coding benchmarks: 67.5 versus 32.5 in the Noometry coding category.

How many benchmarks do Claude Opus 5 and Grok 4 Fast share?

24 benchmarks have published results for both models. Claude Opus 5 has 57 scored results on Noometry and Grok 4 Fast has 30.

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