Noometry

Model comparison

Grok 4.1 Fast vs Llama 3.1-405B

Grok 4.1 Fast is the stronger model overall, scoring 41.4 to 30.7 on the Noometry Index.

Last verified . 21 shared benchmarks.

Grok 4.1 Fast xAI

41.4

Rank #136 Confirmed

Llama 3.1-405B Meta

30.7

Rank #288 Confirmed

Summary

  • They share 21 benchmarks with published results for both. Grok 4.1 Fast scores higher in 9 categories and Llama 3.1-405B in 0 categories; 8 gaps are clear of the uncertainty.
  • The widest gap is in reasoning, where Grok 4.1 Fast leads 43.4 to 16.8.
  • The biggest single-benchmark swing is SimpleBench: 56% for Grok 4.1 Fast and 23% for Llama 3.1-405B.
  • Llama 3.1-405B has downloadable open weights; the other is API-only.

Side by side

Grok 4.1 FastLlama 3.1-405B
ProviderxAIMeta
Noometry Index41.430.7
Released2025-06-272024-07-23
WeightsProprietaryOpen
Context window128K—
Max output30K—
Input $ / M tokens$0.20—
Output $ / M tokens$0.50—
Results tracked3242

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Category by category

Coding Too close to call

Grok 4.1 Fast: 34.1 (#245), Llama 3.1-405B: 33.1 (#262)

BenchmarkGrok 4.1 FastLlama 3.1-405B
LMArena Coding14111291
LMArena WebDev1242—
WeirdML—21.4%
ALE-Bench394.93—

Agentic & Tool Use Grok 4.1 Fast leads

Grok 4.1 Fast: 36.3 (#39), Llama 3.1-405B: 21.0 (#140)

BenchmarkGrok 4.1 FastLlama 3.1-405B
Berkeley Function Calling Leaderboard69.6%—
TheAgentCompany—7.4%
τ²-bench Banking13.1%—
Cybench—7.5%
LMArena Search1171—
Vending-Bench 21,107—

Reasoning Grok 4.1 Fast leads

Grok 4.1 Fast: 43.4 (#49), Llama 3.1-405B: 16.8 (#300)

BenchmarkGrok 4.1 FastLlama 3.1-405B
SimpleBench56%23%
LMArena Hard Prompts14071269
DTBench87.7%61.4%
ForecastBench6159.9
Kagi LLM Benchmark—45%
NYT Connections (extended)87.4%—
BIG-Bench Hard—82.9%
Epoch Capabilities Index—128.75
HellaSwag—89.2%
PIQA—85.9%
WinoGrande—89.2%

Math Grok 4.1 Fast leads

Grok 4.1 Fast: 31.9 (#221), Llama 3.1-405B: 18.4 (#290)

BenchmarkGrok 4.1 FastLlama 3.1-405B
LMArena Math14081281
MathArena Final-Answer Competitions60.9%—
OTIS Mock AIME 2024-2025—9.7%
ProofBench4%—
Omni-MATH—24.9%
MATH Level 5—49.8%

Knowledge Grok 4.1 Fast leads

Grok 4.1 Fast: 33.1 (#207), Llama 3.1-405B: 30.4 (#227)

BenchmarkGrok 4.1 FastLlama 3.1-405B
LMArena Expert13991243
GPQA Diamond—50.9%
MMLU-Pro—72.3%
Confabulations—17.6%
Vectara Hallucination Rate17.8%—
GPQA (HELM)—52.2%
ARC (AI2) Challenge—95.3%
MMLU—84.5%
TriviaQA—82.7%

Multimodal Not comparable

Grok 4.1 Fast: 37.0 (#76), Llama 3.1-405B: —

BenchmarkGrok 4.1 FastLlama 3.1-405B
LMArena Vision1201—

Multilingual Grok 4.1 Fast leads

Grok 4.1 Fast: 51.0 (#114), Llama 3.1-405B: 40.7 (#214)

BenchmarkGrok 4.1 FastLlama 3.1-405B
LMArena Non-English13911248
LMArena Chinese14411242
LMArena French14151279
LMArena German14041252
LMArena Japanese13491208
LMArena Korean13611184
LMArena Russian13871265
LMArena Spanish14131260

Instruction Following Grok 4.1 Fast leads

Grok 4.1 Fast: 72.7 (#133), Llama 3.1-405B: 65.9 (#214)

BenchmarkGrok 4.1 FastLlama 3.1-405B
LMArena Instruction Following13761259
IFEval—81.1%

Long Context Grok 4.1 Fast leads

Grok 4.1 Fast: 42.4 (#126), Llama 3.1-405B: 38.4 (#197)

BenchmarkGrok 4.1 FastLlama 3.1-405B
LMArena Longer Query13901266

Writing & Preference Grok 4.1 Fast leads

Grok 4.1 Fast: 57.2 (#131), Llama 3.1-405B: 38.9 (#251)

BenchmarkGrok 4.1 FastLlama 3.1-405B
LMArena Text14081284
LMArena Creative Writing13941262
EQ-Bench Creative Writing1327870
LMArena Multi-Turn13891297
WildBench—78.3%

Frequently asked questions

Is Grok 4.1 Fast better than Llama 3.1-405B?

Grok 4.1 Fast is the stronger model overall, scoring 41.4 to 30.7 on the Noometry Index.

Is Grok 4.1 Fast or Llama 3.1-405B better for coding?

They score almost the same on coding (34.1 vs 33.1); test both on your own repository before choosing.

How many benchmarks do Grok 4.1 Fast and Llama 3.1-405B share?

21 benchmarks have published results for both models. Grok 4.1 Fast has 32 scored results on Noometry and Llama 3.1-405B has 42.

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