Noometry

Model comparison

Grok 4 Fast vs Llama 3.1-8B

Grok 4 Fast is the stronger model overall, scoring 39.4 to 23.0 on the Noometry Index.

Last verified . 20 shared benchmarks.

Grok 4 Fast xAI

39.4

Rank #167 Confirmed

Llama 3.1-8B Meta

23.0

Rank #352 Confirmed

Summary

  • They share 20 benchmarks with published results for both. Grok 4 Fast scores higher in 9 categories and Llama 3.1-8B in 0 categories; 9 gaps are clear of the uncertainty.
  • The widest gap is in writing & preference, where Grok 4 Fast leads 60.0 to 29.7.
  • The biggest single-benchmark swing is WeirdML: 42.9% for Grok 4 Fast and 1.7% for Llama 3.1-8B.
  • Llama 3.1-8B has downloadable open weights; the other is API-only.

Side by side

Grok 4 FastLlama 3.1-8B
ProviderxAIMeta
Noometry Index39.423.0
Released2025-09-192024-07-23
WeightsProprietaryOpen
Context window—128K
Max output—4K
Input $ / M tokens—$0.05
Output $ / M tokens—$0.08
Results tracked3043

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Category by category

Coding Grok 4 Fast leads

Grok 4 Fast: 32.5 (#271), Llama 3.1-8B: 20.2 (#340)

BenchmarkGrok 4 FastLlama 3.1-8B
WeirdML42.9%1.7%
LMArena Coding14291195
LMArena WebDev1159—
SciCode—13.2%
BigCodeBench Instruct—32.8%
BigCodeBench Complete—40.5%
HumanEval+—62.8%
MBPP+—55.6%

Agentic & Tool Use Grok 4 Fast leads

Grok 4 Fast: 29.5 (#86), Llama 3.1-8B: 22.5 (#131)

BenchmarkGrok 4 FastLlama 3.1-8B
Berkeley Function Calling Leaderboard—25.8%
τ²-bench Banking15.7%—
Cybench30%—
BALROG—15.1%
LMArena Search1171—

Reasoning Grok 4 Fast leads

Grok 4 Fast: 22.2 (#201), Llama 3.1-8B: 14.9 (#321)

BenchmarkGrok 4 FastLlama 3.1-8B
LMArena Hard Prompts14121175
DTBench82.7%50.9%
Epoch Capabilities Index144.2116.57
ARC-AGI-25.3%—
Kagi LLM Benchmark66.1%—
ARC-AGI-148.5%—
CritPt—0%
Chess Puzzles—0%
LMCA—5.4%
ForecastBench60.5—
PIQA—81.2%

Math Grok 4 Fast leads

Grok 4 Fast: 38.9 (#123), Llama 3.1-8B: 10.2 (#317)

BenchmarkGrok 4 FastLlama 3.1-8B
LMArena Math14191179
OTIS Mock AIME 2024-2025—1.7%
Omni-MATH—13.7%
MATH Level 5—22.9%
GSM8K—82.4%

Knowledge Grok 4 Fast leads

Grok 4 Fast: 32.0 (#214), Llama 3.1-8B: 8.0 (#307)

BenchmarkGrok 4 FastLlama 3.1-8B
LMArena Expert14111144
GPQA Diamond—27%
MMLU-Pro—40.6%
Vectara Hallucination Rate19.7%—
GPQA (HELM)—24.7%
BoolQ—82.8%
MMLU—56.1%

Multilingual Grok 4 Fast leads

Grok 4 Fast: 51.3 (#111), Llama 3.1-8B: 34.0 (#249)

BenchmarkGrok 4 FastLlama 3.1-8B
LMArena Non-English13961148
LMArena Chinese14571151
LMArena French14311177
LMArena German13831144
LMArena Japanese13521061
LMArena Korean13571053
LMArena Russian13891158
LMArena Spanish14151169

Instruction Following Grok 4 Fast leads

Grok 4 Fast: 73.2 (#121), Llama 3.1-8B: 58.9 (#258)

BenchmarkGrok 4 FastLlama 3.1-8B
LMArena Instruction Following13871159
IFEval—74.3%

Long Context Grok 4 Fast leads

Grok 4 Fast: 63.2 (#3), Llama 3.1-8B: 35.8 (#238)

BenchmarkGrok 4 FastLlama 3.1-8B
LMArena Longer Query14151182
Fiction.LiveBench94.4%—

Writing & Preference Grok 4 Fast leads

Grok 4 Fast: 60.0 (#102), Llama 3.1-8B: 29.7 (#290)

BenchmarkGrok 4 FastLlama 3.1-8B
LMArena Text14071187
LMArena Creative Writing13871154
LMArena Multi-Turn14141172
EQ-Bench Creative Writing—713
WildBench—68.7%

Frequently asked questions

Is Grok 4 Fast better than Llama 3.1-8B?

Grok 4 Fast is the stronger model overall, scoring 39.4 to 23.0 on the Noometry Index.

Is Grok 4 Fast or Llama 3.1-8B better for coding?

Grok 4 Fast scores higher on coding benchmarks: 32.5 versus 20.2 in the Noometry coding category.

How many benchmarks do Grok 4 Fast and Llama 3.1-8B share?

20 benchmarks have published results for both models. Grok 4 Fast has 30 scored results on Noometry and Llama 3.1-8B has 43.

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