Noometry

Model comparison

Claude Opus 4.8 vs Grok 4 Fast

Claude Opus 4.8 is the stronger model overall, scoring 60.7 to 39.4 on the Noometry Index.

Last verified . 27 shared benchmarks.

Claude Opus 4.8 Anthropic

60.7

Rank #13 Confirmed

Grok 4 Fast xAI

39.4

Rank #167 Confirmed

Summary

  • They share 27 benchmarks with published results for both. Claude Opus 4.8 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 4.8 leads 64.7 to 22.2.
  • The biggest single-benchmark swing is ARC-AGI-2: 72.1% for Claude Opus 4.8 and 5.3% for Grok 4 Fast.

Side by side

Claude Opus 4.8Grok 4 Fast
ProviderAnthropicxAI
Noometry Index60.739.4
Released2026-05-282025-09-19
WeightsProprietaryProprietary
Context window1M—
Max output128K—
Input $ / M tokens$5—
Output $ / M tokens$25—
Results tracked6530

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Category by category

Coding Claude Opus 4.8 leads

Claude Opus 4.8: 59.9 (#12), Grok 4 Fast: 32.5 (#271)

BenchmarkClaude Opus 4.8Grok 4 Fast
LMArena WebDev15561159
WeirdML82.9%42.9%
LMArena Coding14901429
DeepSWE59%—
FrontierCode46.5%—
SciCode53.5%—
GSO47.1%—
ALE-Bench1,564—

Agentic & Tool Use Claude Opus 4.8 leads

Claude Opus 4.8: 47.6 (#11), Grok 4 Fast: 29.5 (#86)

BenchmarkClaude Opus 4.8Grok 4 Fast
τ²-bench Banking39.7%15.7%
LMArena Search12041171
APEX-Agents48.9%—
OSWorld 2.020.6%—
Remote Labor Index8.3%—
Cybench—30%
DeepResearch Bench50.2%—
PostTrainBench33.8%—
GBAEval70.9%—
GDP.pdf24%—
Vending-Bench 25,787—

Reasoning Claude Opus 4.8 leads

Claude Opus 4.8: 64.7 (#16), Grok 4 Fast: 22.2 (#201)

BenchmarkClaude Opus 4.8Grok 4 Fast
ARC-AGI-272.1%5.3%
Kagi LLM Benchmark88.8%66.1%
ARC-AGI-192.5%48.5%
LMArena Hard Prompts14821412
DTBench94.9%82.7%
Epoch Capabilities Index158.21144.2
ForecastBench59.960.5
SimpleBench64.8%—
NYT Connections (extended)91.1%—
CritPt20.9%—
Chess Puzzles34%—
EnigmaEval23.5%—
EBR-Bench28.6%—
Mystery Game Puzzles36%—
LMCA57.5%—
Surface Evolver Bench87.5%—
Bench to the Future 30.14—

Math Claude Opus 4.8 leads

Claude Opus 4.8: 78.4 (#13), Grok 4 Fast: 38.9 (#123)

BenchmarkClaude Opus 4.8Grok 4 Fast
LMArena Math14871419
FrontierMath (Tiers 1-3)80%—
FrontierMath Tier 456.1%—
MathArena Final-Answer Competitions91.8%—
OTIS Mock AIME 2024-202598.3%—
ProofBench69%—
FrontierMath (Feb 2025 set)47.2%—
FrontierMath Tier 4 (v1)31.3%—

Knowledge Claude Opus 4.8 leads

Claude Opus 4.8: 61.3 (#29), Grok 4 Fast: 32.0 (#214)

BenchmarkClaude Opus 4.8Grok 4 Fast
LMArena Expert15021411
GPQA Diamond91%—
SimpleQA Verified53%—
Vectara Hallucination Rate—19.7%

Multimodal Not comparable

Claude Opus 4.8: 42.9 (#26), Grok 4 Fast: —

BenchmarkClaude Opus 4.8Grok 4 Fast
LMArena Vision1294—
Blueprint-Bench 214.5%—
Furniture Assembly42.5%—
LMArena Document1475—

Multilingual Claude Opus 4.8 leads

Claude Opus 4.8: 55.2 (#33), Grok 4 Fast: 51.3 (#111)

BenchmarkClaude Opus 4.8Grok 4 Fast
LMArena Non-English14501396
LMArena Chinese15071457
LMArena French14811431
LMArena German14721383
LMArena Japanese14401352
LMArena Korean14321357
LMArena Russian14741389
LMArena Spanish14661415

Instruction Following Claude Opus 4.8 leads

Claude Opus 4.8: 77.4 (#24), Grok 4 Fast: 73.2 (#121)

BenchmarkClaude Opus 4.8Grok 4 Fast
LMArena Instruction Following14761387

Long Context Grok 4 Fast leads

Claude Opus 4.8: 45.4 (#35), Grok 4 Fast: 63.2 (#3)

BenchmarkClaude Opus 4.8Grok 4 Fast
LMArena Longer Query14831415
Fiction.LiveBench—94.4%

Writing & Preference Claude Opus 4.8 leads

Claude Opus 4.8: 72.0 (#16), Grok 4 Fast: 60.0 (#102)

BenchmarkClaude Opus 4.8Grok 4 Fast
LMArena Text14611407
LMArena Creative Writing14541387
LMArena Multi-Turn14761414
EQ-Bench Creative Writing1840—
EQ-Bench 41281—

Frequently asked questions

Is Claude Opus 4.8 better than Grok 4 Fast?

Claude Opus 4.8 is the stronger model overall, scoring 60.7 to 39.4 on the Noometry Index.

Is Claude Opus 4.8 or Grok 4 Fast better for coding?

Claude Opus 4.8 scores higher on coding benchmarks: 59.9 versus 32.5 in the Noometry coding category.

How many benchmarks do Claude Opus 4.8 and Grok 4 Fast share?

27 benchmarks have published results for both models. Claude Opus 4.8 has 65 scored results on Noometry and Grok 4 Fast has 30.

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