Noometry

Model comparison

GPT-5 Nano vs Grok 4 Fast

Grok 4 Fast is the stronger model overall, scoring 39.0 to 33.4 on the Noometry Index.

Last verified . 24 shared benchmarks.

GPT-5 Nano OpenAI

33.4

Rank #234 Confirmed

Grok 4 Fast xAI

39.0

Rank #164 Confirmed

Summary

  • They share 24 benchmarks with published results for both. GPT-5 Nano scores higher in 3 categories and Grok 4 Fast in 6 categories; 9 gaps are clear of the uncertainty.
  • The widest gap is in long context, where Grok 4 Fast leads 63.2 to 31.3.
  • The biggest single-benchmark swing is Fiction.LiveBench: 44.4% for GPT-5 Nano and 94.4% for Grok 4 Fast.

Side by side

GPT-5 NanoGrok 4 Fast
ProviderOpenAIxAI
Noometry Index33.439.0
Released2025-08-072025-09-19
WeightsProprietaryProprietary
Context window400K—
Max output128K—
Input $ / M tokens$0.05—
Output $ / M tokens$0.40—
Results tracked4830

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Category by category

Coding GPT-5 Nano leads

GPT-5 Nano: 33.3 (#248), Grok 4 Fast: 32.3 (#264)

BenchmarkGPT-5 NanoGrok 4 Fast
WeirdML38.1%42.9%
LMArena Coding13511429
SWE-bench Verified (bash only)34.8%—
LMArena WebDev—1160
ALE-Bench718.67—

Agentic & Tool Use Grok 4 Fast leads

GPT-5 Nano: 25.6 (#99), Grok 4 Fast: 29.3 (#80)

BenchmarkGPT-5 NanoGrok 4 Fast
Terminal-Bench21.8%—
Berkeley Function Calling Leaderboard51.5%—
τ²-bench Banking—15.7%
Cybench—30%
LMArena Search—1171

Reasoning Grok 4 Fast leads

GPT-5 Nano: 16.4 (#291), Grok 4 Fast: 22.5 (#179)

BenchmarkGPT-5 NanoGrok 4 Fast
ARC-AGI-22.6%5.3%
Kagi LLM Benchmark62.2%66.1%
ARC-AGI-120.7%48.5%
LMArena Hard Prompts13291413
DTBench62.7%82.7%
Epoch Capabilities Index139.39144.21
ForecastBench59.160.5
Chess Puzzles27%—
Mystery Game Puzzles9%—
LMCA7.9%—

Math Grok 4 Fast leads

GPT-5 Nano: 29.1 (#221), Grok 4 Fast: 36.1 (#126)

BenchmarkGPT-5 NanoGrok 4 Fast
LMArena Math13181419
FrontierMath (Tiers 1-3)20%—
FrontierMath Tier 42.4%—
OTIS Mock AIME 2024-202581.1%—
ProofBench12%—
Omni-MATH54.6%—
MATH Level 595.2%—
FrontierMath (Feb 2025 set)8.3%—
FrontierMath Tier 4 (v1)2.1%—

Knowledge GPT-5 Nano leads

GPT-5 Nano: 35.8 (#166), Grok 4 Fast: 31.5 (#211)

BenchmarkGPT-5 NanoGrok 4 Fast
Vectara Hallucination Rate10.5%19.7%
LMArena Expert13211411
GPQA Diamond69.4%—
SimpleQA Verified11.7%—
MMLU-Pro77.8%—
GPQA (HELM)67.9%—

Multimodal Not comparable

GPT-5 Nano: 30.7 (#102), Grok 4 Fast: —

BenchmarkGPT-5 NanoGrok 4 Fast
LMArena Vision1159—
VPCT37.2%—

Multilingual Grok 4 Fast leads

GPT-5 Nano: 45.5 (#167), Grok 4 Fast: 51.5 (#106)

BenchmarkGPT-5 NanoGrok 4 Fast
LMArena Non-English13131397
LMArena Chinese13551458
LMArena German13291383
LMArena Korean12691359
LMArena Russian12961387
LMArena Spanish13601414
LMArena French—1433
LMArena Japanese—1358

Instruction Following GPT-5 Nano leads

GPT-5 Nano: 75.2 (#72), Grok 4 Fast: 73.4 (#116)

BenchmarkGPT-5 NanoGrok 4 Fast
LMArena Instruction Following13061388
IFEval93.2%—

Long Context Grok 4 Fast leads

GPT-5 Nano: 31.3 (#275), Grok 4 Fast: 63.2 (#3)

BenchmarkGPT-5 NanoGrok 4 Fast
Fiction.LiveBench44.4%94.4%
LMArena Longer Query13131415

Writing & Preference Grok 4 Fast leads

GPT-5 Nano: 39.4 (#244), Grok 4 Fast: 60.2 (#96)

BenchmarkGPT-5 NanoGrok 4 Fast
LMArena Text13201407
LMArena Creative Writing12501388
LMArena Multi-Turn13111414
EQ-Bench Creative Writing705—
WildBench80.6%—

Frequently asked questions

Is GPT-5 Nano better than Grok 4 Fast?

Grok 4 Fast is the stronger model overall, scoring 39.0 to 33.4 on the Noometry Index.

Is GPT-5 Nano or Grok 4 Fast better for coding?

GPT-5 Nano scores higher on coding benchmarks: 33.3 versus 32.3 in the Noometry coding category.

How many benchmarks do GPT-5 Nano and Grok 4 Fast share?

24 benchmarks have published results for both models. GPT-5 Nano has 48 scored results on Noometry and Grok 4 Fast has 30.

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