Noometry

Model comparison

GPT-5.3 Chat vs Grok 4.1 Fast

GPT-5.3 Chat is the stronger model overall, scoring 42.8 to 41.4 on the Noometry Index. Grok 4.1 Fast costs 18× less per token, which makes it the better buy when GPT-5.3 Chat's lead doesn't matter for your workload.

Last verified . 18 shared benchmarks.

GPT-5.3 Chat OpenAI

42.8

Rank #109 Confirmed

Grok 4.1 Fast xAI

41.4

Rank #136 Confirmed

Summary

  • They share 18 benchmarks with published results for both. GPT-5.3 Chat scores higher in 6 categories and Grok 4.1 Fast in 2 categories; 5 gaps are clear of the uncertainty.
  • The widest gap is in reasoning, where Grok 4.1 Fast leads 43.4 to 28.5.
  • Grok 4.1 Fast is cheaper at $0.20 / $0.50 per million input/output tokens, against $1.75 / $14 for GPT-5.3 Chat.

Side by side

GPT-5.3 ChatGrok 4.1 Fast
ProviderOpenAIxAI
Noometry Index42.841.4
Released2026-03-032025-06-27
WeightsProprietaryProprietary
Context window128K128K
Max output16K30K
Input $ / M tokens$1.75$0.20
Output $ / M tokens$14$0.50
Results tracked1832

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Category by category

Coding GPT-5.3 Chat leads

GPT-5.3 Chat: 41.4 (#124), Grok 4.1 Fast: 34.1 (#245)

BenchmarkGPT-5.3 ChatGrok 4.1 Fast
LMArena Coding14081411
LMArena WebDev—1242
ALE-Bench—394.93

Agentic & Tool Use Not comparable

GPT-5.3 Chat: —, Grok 4.1 Fast: 36.3 (#39)

BenchmarkGPT-5.3 ChatGrok 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

GPT-5.3 Chat: 28.5 (#102), Grok 4.1 Fast: 43.4 (#49)

BenchmarkGPT-5.3 ChatGrok 4.1 Fast
LMArena Hard Prompts13991407
SimpleBench—56%
NYT Connections (extended)—87.4%
DTBench—87.7%
ForecastBench—61

Math GPT-5.3 Chat leads

GPT-5.3 Chat: 38.2 (#142), Grok 4.1 Fast: 31.9 (#221)

BenchmarkGPT-5.3 ChatGrok 4.1 Fast
LMArena Math13891408
MathArena Final-Answer Competitions—60.9%
ProofBench—4%

Knowledge GPT-5.3 Chat leads

GPT-5.3 Chat: 38.8 (#140), Grok 4.1 Fast: 33.1 (#207)

BenchmarkGPT-5.3 ChatGrok 4.1 Fast
LMArena Expert13971399
Vectara Hallucination Rate—17.8%

Multimodal Not comparable

GPT-5.3 Chat: —, Grok 4.1 Fast: 37.0 (#76)

BenchmarkGPT-5.3 ChatGrok 4.1 Fast
LMArena Vision—1201

Multilingual Too close to call

GPT-5.3 Chat: 50.3 (#124), Grok 4.1 Fast: 51.0 (#114)

BenchmarkGPT-5.3 ChatGrok 4.1 Fast
LMArena Non-English13821391
LMArena Chinese14321441
LMArena French13971415
LMArena German13841404
LMArena Japanese13521349
LMArena Korean13461361
LMArena Russian14001387
LMArena Spanish13711413

Instruction Following Too close to call

GPT-5.3 Chat: 72.8 (#129), Grok 4.1 Fast: 72.7 (#133)

BenchmarkGPT-5.3 ChatGrok 4.1 Fast
LMArena Instruction Following13781376

Long Context Too close to call

GPT-5.3 Chat: 42.6 (#120), Grok 4.1 Fast: 42.4 (#126)

BenchmarkGPT-5.3 ChatGrok 4.1 Fast
LMArena Longer Query13961390

Writing & Preference GPT-5.3 Chat leads

GPT-5.3 Chat: 63.1 (#68), Grok 4.1 Fast: 57.2 (#131)

BenchmarkGPT-5.3 ChatGrok 4.1 Fast
LMArena Text13891408
LMArena Creative Writing13551394
EQ-Bench Creative Writing16901327
LMArena Multi-Turn14121389

Frequently asked questions

Is GPT-5.3 Chat better than Grok 4.1 Fast?

GPT-5.3 Chat is the stronger model overall, scoring 42.8 to 41.4 on the Noometry Index. Grok 4.1 Fast costs 18× less per token, which makes it the better buy when GPT-5.3 Chat's lead doesn't matter for your workload.

Which is cheaper, GPT-5.3 Chat 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; GPT-5.3 Chat lists at $1.75 and $14.

Is GPT-5.3 Chat or Grok 4.1 Fast better for coding?

GPT-5.3 Chat scores higher on coding benchmarks: 41.4 versus 34.1 in the Noometry coding category.

Which has the bigger context window?

Both accept 128K tokens.

How many benchmarks do GPT-5.3 Chat and Grok 4.1 Fast share?

18 benchmarks have published results for both models. GPT-5.3 Chat has 18 scored results on Noometry and Grok 4.1 Fast has 32.

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