Noometry

Model comparison

GLM-4.5-Air vs Grok 4.1 Fast

Grok 4.1 Fast is the stronger model overall, scoring 40.9 to 38.7 on the Noometry Index.

Last verified . 19 shared benchmarks.

GLM-4.5-Air Z.ai (Zhipu)

38.7

Rank #169 Confirmed

Grok 4.1 Fast xAI

40.9

Rank #131 Confirmed

Summary

  • They share 19 benchmarks with published results for both. GLM-4.5-Air scores higher in 3 categories and Grok 4.1 Fast in 5 categories; 6 gaps are clear of the uncertainty.
  • The widest gap is in reasoning, where Grok 4.1 Fast leads 42.3 to 23.3.
  • The biggest single-benchmark swing is Vectara Hallucination Rate: 9.3% for GLM-4.5-Air and 17.8% for Grok 4.1 Fast.
  • Grok 4.1 Fast is cheaper at $0.20 / $0.50 per million input/output tokens, against $0.20 / $1.10 for GLM-4.5-Air.
  • GLM-4.5-Air accepts more context: 131K tokens versus 128K.
  • GLM-4.5-Air has downloadable open weights; the other is API-only.

Side by side

GLM-4.5-AirGrok 4.1 Fast
ProviderZ.ai (Zhipu)xAI
Noometry Index38.740.9
Released2025-07-202025-06-27
WeightsOpenProprietary
Context window131K128K
Max output98K30K
Input $ / M tokens$0.20$0.20
Output $ / M tokens$1.10$0.50
Results tracked2732

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Category by category

Coding Too close to call

GLM-4.5-Air: 34.5 (#225), Grok 4.1 Fast: 33.8 (#236)

BenchmarkGLM-4.5-AirGrok 4.1 Fast
LMArena Coding13971411
LMArena WebDev—1241
GSO2.9%—
ALE-Bench—394.93

Agentic & Tool Use Not comparable

GLM-4.5-Air: —, Grok 4.1 Fast: 36.1 (#35)

BenchmarkGLM-4.5-AirGrok 4.1 Fast
Berkeley Function Calling Leaderboard—69.6%
τ²-bench Banking—13.1%
LMArena Search—1171
Vending-Bench 2—1,107

Reasoning Grok 4.1 Fast leads

GLM-4.5-Air: 23.3 (#166), Grok 4.1 Fast: 42.3 (#45)

BenchmarkGLM-4.5-AirGrok 4.1 Fast
LMArena Hard Prompts13791407
ForecastBench59.261
SimpleBench—56%
Kagi LLM Benchmark43%—
NYT Connections (extended)—87.4%
DTBench—87.7%

Math GLM-4.5-Air leads

GLM-4.5-Air: 33.8 (#166), Grok 4.1 Fast: 30.9 (#201)

BenchmarkGLM-4.5-AirGrok 4.1 Fast
LMArena Math13961408
MathArena Final-Answer Competitions—60.9%
ProofBench—4%
Omni-MATH39.1%—

Knowledge GLM-4.5-Air leads

GLM-4.5-Air: 34.6 (#184), Grok 4.1 Fast: 32.6 (#203)

BenchmarkGLM-4.5-AirGrok 4.1 Fast
Vectara Hallucination Rate9.3%17.8%
LMArena Expert13701398
Humanity's Last Exam8.1%—
MMLU-Pro76.2%—
GPQA (HELM)59.4%—

Multimodal Not comparable

GLM-4.5-Air: —, Grok 4.1 Fast: 36.3 (#71)

BenchmarkGLM-4.5-AirGrok 4.1 Fast
LMArena Vision—1201

Multilingual Grok 4.1 Fast leads

GLM-4.5-Air: 49.4 (#130), Grok 4.1 Fast: 51.1 (#110)

BenchmarkGLM-4.5-AirGrok 4.1 Fast
LMArena Non-English13661391
LMArena Chinese14271441
LMArena French13991416
LMArena German13761404
LMArena Japanese13481347
LMArena Korean13061361
LMArena Russian13731387
LMArena Spanish13851411

Instruction Following Grok 4.1 Fast leads

GLM-4.5-Air: 69.8 (#165), Grok 4.1 Fast: 72.8 (#127)

BenchmarkGLM-4.5-AirGrok 4.1 Fast
LMArena Instruction Following13531376
IFEval81.2%—

Long Context Too close to call

GLM-4.5-Air: 41.6 (#130), Grok 4.1 Fast: 42.4 (#121)

BenchmarkGLM-4.5-AirGrok 4.1 Fast
LMArena Longer Query13671390

Writing & Preference Grok 4.1 Fast leads

GLM-4.5-Air: 56.1 (#134), Grok 4.1 Fast: 57.4 (#126)

BenchmarkGLM-4.5-AirGrok 4.1 Fast
LMArena Text13841408
LMArena Creative Writing13431394
LMArena Multi-Turn13711389
EQ-Bench Creative Writing—1327
WildBench78.9%—

Frequently asked questions

Is GLM-4.5-Air better than Grok 4.1 Fast?

Grok 4.1 Fast is the stronger model overall, scoring 40.9 to 38.7 on the Noometry Index.

Which is cheaper, GLM-4.5-Air or Grok 4.1 Fast?

Grok 4.1 Fast is cheaper. It lists at $0.20 per million input tokens and $0.50 per million output tokens; GLM-4.5-Air lists at $0.20 and $1.10.

Is GLM-4.5-Air or Grok 4.1 Fast better for coding?

They score almost the same on coding (34.5 vs 33.8); test both on your own repository before choosing.

Which has the bigger context window?

GLM-4.5-Air does, with 131K tokens against 128K.

How many benchmarks do GLM-4.5-Air and Grok 4.1 Fast share?

19 benchmarks have published results for both models. GLM-4.5-Air has 27 scored results on Noometry and Grok 4.1 Fast has 32.

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