Noometry

Model comparison

Grok 4.1 Fast vs Grok 4 Fast

Grok 4.1 Fast is the stronger model overall, scoring 41.4 to 39.4 on the Noometry Index.

Last verified . 23 shared benchmarks.

Grok 4.1 Fast xAI

41.4

Rank #136 Confirmed

Grok 4 Fast xAI

39.4

Rank #167 Confirmed

Summary

  • They share 23 benchmarks with published results for both. Grok 4.1 Fast scores higher in 4 categories and Grok 4 Fast in 5 categories; 7 gaps are clear of the uncertainty.
  • The widest gap is in reasoning, where Grok 4.1 Fast leads 43.4 to 22.2.
  • The biggest single-benchmark swing is DTBench: 87.7% for Grok 4.1 Fast and 82.7% for Grok 4 Fast.

Side by side

Grok 4.1 FastGrok 4 Fast
ProviderxAIxAI
Noometry Index41.439.4
Released2025-06-272025-09-19
WeightsProprietaryProprietary
Context window128K—
Max output30K—
Input $ / M tokens$0.20—
Output $ / M tokens$0.50—
Results tracked3230

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Category by category

Coding Grok 4.1 Fast leads

Grok 4.1 Fast: 34.1 (#245), Grok 4 Fast: 32.5 (#271)

BenchmarkGrok 4.1 FastGrok 4 Fast
LMArena WebDev12421159
LMArena Coding14111429
WeirdML—42.9%
ALE-Bench394.93—

Agentic & Tool Use Grok 4.1 Fast leads

Grok 4.1 Fast: 36.3 (#39), Grok 4 Fast: 29.5 (#86)

BenchmarkGrok 4.1 FastGrok 4 Fast
τ²-bench Banking13.1%15.7%
LMArena Search11711171
Berkeley Function Calling Leaderboard69.6%—
Cybench—30%
Vending-Bench 21,107—

Reasoning Grok 4.1 Fast leads

Grok 4.1 Fast: 43.4 (#49), Grok 4 Fast: 22.2 (#201)

BenchmarkGrok 4.1 FastGrok 4 Fast
LMArena Hard Prompts14071412
DTBench87.7%82.7%
ForecastBench6160.5
ARC-AGI-2—5.3%
SimpleBench56%—
Kagi LLM Benchmark—66.1%
NYT Connections (extended)87.4%—
ARC-AGI-1—48.5%
Epoch Capabilities Index—144.2

Math Grok 4 Fast leads

Grok 4.1 Fast: 31.9 (#221), Grok 4 Fast: 38.9 (#123)

BenchmarkGrok 4.1 FastGrok 4 Fast
LMArena Math14081419
MathArena Final-Answer Competitions60.9%—
ProofBench4%—

Knowledge Grok 4.1 Fast leads

Grok 4.1 Fast: 33.1 (#207), Grok 4 Fast: 32.0 (#214)

BenchmarkGrok 4.1 FastGrok 4 Fast
Vectara Hallucination Rate17.8%19.7%
LMArena Expert13991411

Multimodal Not comparable

Grok 4.1 Fast: 37.0 (#76), Grok 4 Fast: —

BenchmarkGrok 4.1 FastGrok 4 Fast
LMArena Vision1201—

Multilingual Too close to call

Grok 4.1 Fast: 51.0 (#114), Grok 4 Fast: 51.3 (#111)

BenchmarkGrok 4.1 FastGrok 4 Fast
LMArena Non-English13911396
LMArena Chinese14411457
LMArena French14151431
LMArena German14041383
LMArena Japanese13491352
LMArena Korean13611357
LMArena Russian13871389
LMArena Spanish14131415

Instruction Following Too close to call

Grok 4.1 Fast: 72.7 (#133), Grok 4 Fast: 73.2 (#121)

BenchmarkGrok 4.1 FastGrok 4 Fast
LMArena Instruction Following13761387

Long Context Grok 4 Fast leads

Grok 4.1 Fast: 42.4 (#126), Grok 4 Fast: 63.2 (#3)

BenchmarkGrok 4.1 FastGrok 4 Fast
LMArena Longer Query13901415
Fiction.LiveBench—94.4%

Writing & Preference Grok 4 Fast leads

Grok 4.1 Fast: 57.2 (#131), Grok 4 Fast: 60.0 (#102)

BenchmarkGrok 4.1 FastGrok 4 Fast
LMArena Text14081407
LMArena Creative Writing13941387
LMArena Multi-Turn13891414
EQ-Bench Creative Writing1327—

Frequently asked questions

Is Grok 4.1 Fast better than Grok 4 Fast?

Grok 4.1 Fast is the stronger model overall, scoring 41.4 to 39.4 on the Noometry Index.

Is Grok 4.1 Fast or Grok 4 Fast better for coding?

Grok 4.1 Fast scores higher on coding benchmarks: 34.1 versus 32.5 in the Noometry coding category.

How many benchmarks do Grok 4.1 Fast and Grok 4 Fast share?

23 benchmarks have published results for both models. Grok 4.1 Fast has 32 scored results on Noometry and Grok 4 Fast has 30.

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