Noometry

Model comparison

Grok 4 Fast vs Kimi K3

Kimi K3 is the stronger model overall, scoring 59.5 to 39.4 on the Noometry Index.

Last verified . 25 shared benchmarks.

Grok 4 Fast xAI

39.4

Rank #167 Confirmed

Kimi K3 Moonshot AI

59.5

Rank #15 Confirmed

Summary

  • They share 25 benchmarks with published results for both. Grok 4 Fast scores higher in 1 category and Kimi K3 in 8 categories; 9 gaps are clear of the uncertainty.
  • The widest gap is in reasoning, where Kimi K3 leads 63.0 to 22.2.
  • The biggest single-benchmark swing is ARC-AGI-2: 5.3% for Grok 4 Fast and 60.4% for Kimi K3.
  • Kimi K3 has downloadable open weights; the other is API-only.

Side by side

Grok 4 FastKimi K3
ProviderxAIMoonshot AI
Noometry Index39.459.5
Released2025-09-192026-07-16
WeightsProprietaryOpen
Context window—1.05M
Max output—1.05M
Input $ / M tokens—$3
Output $ / M tokens—$15
Results tracked3053

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Category by category

Coding Kimi K3 leads

Grok 4 Fast: 32.5 (#271), Kimi K3: 61.0 (#10)

BenchmarkGrok 4 FastKimi K3
LMArena WebDev11591654
WeirdML42.9%82.6%
LMArena Coding14291508
DeepSWE—68.5%
FrontierCode—44.2%
FrontierSWE—25.9%
SciCode—59.5%
ALE-Bench—1,524

Agentic & Tool Use Kimi K3 leads

Grok 4 Fast: 29.5 (#86), Kimi K3: 41.8 (#20)

BenchmarkGrok 4 FastKimi K3
τ²-bench Banking15.7%37.1%
APEX-Agents—50.6%
Cybench30%—
PostTrainBench—32%
GBAEval—48.3%
GDP.pdf—19%
LMArena Search1171—
Vending-Bench 2—5,165

Reasoning Kimi K3 leads

Grok 4 Fast: 22.2 (#201), Kimi K3: 63.0 (#17)

BenchmarkGrok 4 FastKimi K3
ARC-AGI-25.3%60.4%
ARC-AGI-148.5%94.5%
LMArena Hard Prompts14121496
DTBench82.7%91.2%
Epoch Capabilities Index144.2157.45
ForecastBench60.561.1
SimpleBench—60.7%
Kagi LLM Benchmark66.1%—
NYT Connections (extended)—93.6%
CritPt—23.4%
Chess Puzzles—39%
Mystery Game Puzzles—26%
LMCA—52.7%
Surface Evolver Bench—95%

Math Kimi K3 leads

Grok 4 Fast: 38.9 (#123), Kimi K3: 74.2 (#16)

BenchmarkGrok 4 FastKimi K3
LMArena Math14191491
FrontierMath (Tiers 1-3)—72.2%
FrontierMath Tier 4—39%
MathArena Final-Answer Competitions—87.8%
OTIS Mock AIME 2024-2025—97.2%
ProofBench—87%

Knowledge Kimi K3 leads

Grok 4 Fast: 32.0 (#214), Kimi K3: 63.2 (#21)

BenchmarkGrok 4 FastKimi K3
LMArena Expert14111521
GPQA Diamond—93.1%
SimpleQA Verified—50.6%
Vectara Hallucination Rate19.7%—

Multimodal Not comparable

Grok 4 Fast: —, Kimi K3: 37.8 (#70)

BenchmarkGrok 4 FastKimi K3
Blueprint-Bench 2—29.5%
Furniture Assembly—34.2%

Multilingual Kimi K3 leads

Grok 4 Fast: 51.3 (#111), Kimi K3: 56.3 (#21)

BenchmarkGrok 4 FastKimi K3
LMArena Non-English13961466
LMArena Chinese14571529
LMArena French14311491
LMArena German13831488
LMArena Japanese13521487
LMArena Korean13571458
LMArena Russian13891482
LMArena Spanish14151472

Instruction Following Kimi K3 leads

Grok 4 Fast: 73.2 (#121), Kimi K3: 77.7 (#14)

BenchmarkGrok 4 FastKimi K3
LMArena Instruction Following13871483

Long Context Grok 4 Fast leads

Grok 4 Fast: 63.2 (#3), Kimi K3: 45.8 (#29)

BenchmarkGrok 4 FastKimi K3
LMArena Longer Query14151494
Fiction.LiveBench94.4%—

Writing & Preference Kimi K3 leads

Grok 4 Fast: 60.0 (#102), Kimi K3: 76.6 (#4)

BenchmarkGrok 4 FastKimi K3
LMArena Text14071476
LMArena Creative Writing13871454
LMArena Multi-Turn14141488
EQ-Bench Creative Writing—2082
EQ-Bench 4—1339

Frequently asked questions

Is Grok 4 Fast better than Kimi K3?

Kimi K3 is the stronger model overall, scoring 59.5 to 39.4 on the Noometry Index.

Is Grok 4 Fast or Kimi K3 better for coding?

Kimi K3 scores higher on coding benchmarks: 61.0 versus 32.5 in the Noometry coding category.

How many benchmarks do Grok 4 Fast and Kimi K3 share?

25 benchmarks have published results for both models. Grok 4 Fast has 30 scored results on Noometry and Kimi K3 has 53.

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