Noometry

Model comparison

Grok 4.6 vs Grok 4 Fast

Grok 4.6 is the stronger model overall, scoring 56.9 to 39.4 on the Noometry Index.

Last verified . 23 shared benchmarks.

Grok 4.6 xAI

56.9

Rank #21 Confirmed

Grok 4 Fast xAI

39.4

Rank #167 Confirmed

Summary

  • They share 23 benchmarks with published results for both. Grok 4.6 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 Grok 4.6 leads 61.4 to 22.2.
  • The biggest single-benchmark swing is ARC-AGI-2: 67.1% for Grok 4.6 and 5.3% for Grok 4 Fast.

Side by side

Grok 4.6Grok 4 Fast
ProviderxAIxAI
Noometry Index56.939.4
Released2026-08-122025-09-19
WeightsProprietaryProprietary
Context window500K—
Max output500K—
Input $ / M tokens$2—
Output $ / M tokens$6—
Results tracked4930

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Category by category

Coding Grok 4.6 leads

Grok 4.6: 58.5 (#16), Grok 4 Fast: 32.5 (#271)

BenchmarkGrok 4.6Grok 4 Fast
LMArena WebDev16171159
WeirdML67.3%42.9%
LMArena Coding14651429
DeepSWE67.5%—
FrontierCode48%—
CursorBench41.4%—
FrontierSWE25.3%—
SciCode56.5%—
ALE-Bench1,508—

Agentic & Tool Use Grok 4.6 leads

Grok 4.6: 39.4 (#27), Grok 4 Fast: 29.5 (#86)

BenchmarkGrok 4.6Grok 4 Fast
APEX-Agents65.3%—
τ²-bench Banking—15.7%
Cybench—30%
GDP.pdf17.2%—
LMArena Search—1171
Vending-Bench 29,047—

Reasoning Grok 4.6 leads

Grok 4.6: 61.4 (#20), Grok 4 Fast: 22.2 (#201)

BenchmarkGrok 4.6Grok 4 Fast
ARC-AGI-267.1%5.3%
ARC-AGI-187.5%48.5%
LMArena Hard Prompts14471412
DTBench97.3%82.7%
Epoch Capabilities Index156.44144.2
SimpleBench75.9%—
Kagi LLM Benchmark—66.1%
NYT Connections (extended)80%—
CritPt19.7%—
Chess Puzzles40%—
EBR-Bench30.5%—
Mystery Game Puzzles34%—
LMCA48.5%—
ForecastBench—60.5

Math Grok 4.6 leads

Grok 4.6: 67.0 (#24), Grok 4 Fast: 38.9 (#123)

BenchmarkGrok 4.6Grok 4 Fast
LMArena Math14231419
FrontierMath (Tiers 1-3)66%—
FrontierMath Tier 431.7%—
OTIS Mock AIME 2024-202599.2%—
ProofBench51%—

Knowledge Grok 4.6 leads

Grok 4.6: 63.3 (#20), Grok 4 Fast: 32.0 (#214)

BenchmarkGrok 4.6Grok 4 Fast
LMArena Expert14671411
GPQA Diamond94%—
SimpleQA Verified49.3%—
Vectara Hallucination Rate—19.7%

Multimodal Not comparable

Grok 4.6: 43.6 (#23), Grok 4 Fast: —

BenchmarkGrok 4.6Grok 4 Fast
LMArena Vision1263—
Blueprint-Bench 233.2%—
Furniture Assembly40%—
LMArena Document1452—

Multilingual Grok 4.6 leads

Grok 4.6: 53.0 (#74), Grok 4 Fast: 51.3 (#111)

BenchmarkGrok 4.6Grok 4 Fast
LMArena Non-English14201396
LMArena Chinese14801457
LMArena French14611431
LMArena German14311383
LMArena Japanese13761352
LMArena Korean13971357
LMArena Russian14221389
LMArena Spanish14041415

Instruction Following Grok 4.6 leads

Grok 4.6: 75.4 (#63), Grok 4 Fast: 73.2 (#121)

BenchmarkGrok 4.6Grok 4 Fast
LMArena Instruction Following14311387

Long Context Grok 4 Fast leads

Grok 4.6: 44.5 (#66), Grok 4 Fast: 63.2 (#3)

BenchmarkGrok 4.6Grok 4 Fast
LMArena Longer Query14541415
Fiction.LiveBench—94.4%

Writing & Preference Grok 4.6 leads

Grok 4.6: 62.3 (#80), Grok 4 Fast: 60.0 (#102)

BenchmarkGrok 4.6Grok 4 Fast
LMArena Text14281407
LMArena Creative Writing14281387
LMArena Multi-Turn14251414

Frequently asked questions

Is Grok 4.6 better than Grok 4 Fast?

Grok 4.6 is the stronger model overall, scoring 56.9 to 39.4 on the Noometry Index.

Is Grok 4.6 or Grok 4 Fast better for coding?

Grok 4.6 scores higher on coding benchmarks: 58.5 versus 32.5 in the Noometry coding category.

How many benchmarks do Grok 4.6 and Grok 4 Fast share?

23 benchmarks have published results for both models. Grok 4.6 has 49 scored results on Noometry and Grok 4 Fast has 30.

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