Noometry

Model comparison

GPT-5-Codex vs Grok 4.3

Grok 4.3 is the stronger model overall, scoring 43.8 to 37.9 on the Noometry Index.

Last verified . 1 shared benchmarks.

GPT-5-Codex OpenAI

37.9

Rank #192 Reported

Grok 4.3 xAI

43.8

Rank #86 Confirmed

Summary

  • They share 1 benchmark with published results for both. GPT-5-Codex scores higher in 2 categories and Grok 4.3 in 1 category; 2 gaps are clear of the uncertainty.
  • The widest gap is in reasoning, where Grok 4.3 leads 35.9 to 30.9.
  • Grok 4.3 is cheaper at $1.25 / $2.50 per million input/output tokens, against $1.25 / $10 for GPT-5-Codex.
  • Grok 4.3 accepts more context: 1M tokens versus 400K.

Side by side

GPT-5-CodexGrok 4.3
ProviderOpenAIxAI
Noometry Index37.943.8
Released2025-09-152026-04-17
WeightsProprietaryProprietary
Context window400K1M
Max output128K30K
Input $ / M tokens$1.25$1.25
Output $ / M tokens$10$2.50
Results tracked340

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Category by category

Coding Too close to call

GPT-5-Codex: 42.4 (#103), Grok 4.3: 41.6 (#121)

BenchmarkGPT-5-CodexGrok 4.3
WeirdML54.5%49.9%
LMArena WebDev—1357
SciCode—47.3%
LMArena Coding—1415
ALE-Bench—944.17

Agentic & Tool Use GPT-5-Codex leads

GPT-5-Codex: 31.0 (#72), Grok 4.3: 27.7 (#99)

BenchmarkGPT-5-CodexGrok 4.3
Terminal-Bench44.3%—
GDP.pdf—8%
LMArena Search—1165
Vending-Bench 2—35.26

Reasoning Grok 4.3 leads

GPT-5-Codex: 30.9 (#83), Grok 4.3: 35.9 (#68)

BenchmarkGPT-5-CodexGrok 4.3
Kagi LLM Benchmark70.3%—
NYT Connections (extended)—55.2%
CritPt—8%
Chess Puzzles—25%
LMArena Hard Prompts—1396
DTBench—90.7%
LMCA—38.3%
Epoch Capabilities Index—149.16
ForecastBench—60.3

Math Not comparable

GPT-5-Codex: —, Grok 4.3: 46.0 (#74)

BenchmarkGPT-5-CodexGrok 4.3
FrontierMath (Tiers 1-3)—42.8%
FrontierMath Tier 4—14.6%
OTIS Mock AIME 2024-2025—93.3%
ProofBench—11%
LMArena Math—1388

Knowledge Not comparable

GPT-5-Codex: —, Grok 4.3: 52.5 (#62)

BenchmarkGPT-5-CodexGrok 4.3
GPQA Diamond—88.8%
SimpleQA Verified—33.2%
LMArena Expert—1385

Multimodal Not comparable

GPT-5-Codex: —, Grok 4.3: 31.6 (#104)

BenchmarkGPT-5-CodexGrok 4.3
LMArena Vision—1229
Blueprint-Bench 2—0%

Multilingual Not comparable

GPT-5-Codex: —, Grok 4.3: 50.5 (#120)

BenchmarkGPT-5-CodexGrok 4.3
LMArena Non-English—1385
LMArena Chinese—1422
LMArena French—1412
LMArena German—1395
LMArena Japanese—1379
LMArena Korean—1356
LMArena Russian—1399
LMArena Spanish—1398

Instruction Following Not comparable

GPT-5-Codex: —, Grok 4.3: 72.1 (#140)

BenchmarkGPT-5-CodexGrok 4.3
LMArena Instruction Following—1366

Long Context Not comparable

GPT-5-Codex: —, Grok 4.3: 42.5 (#123)

BenchmarkGPT-5-CodexGrok 4.3
LMArena Longer Query—1393

Writing & Preference Not comparable

GPT-5-Codex: —, Grok 4.3: 58.5 (#118)

BenchmarkGPT-5-CodexGrok 4.3
LMArena Text—1397
LMArena Creative Writing—1380
EQ-Bench 4—1075
LMArena Multi-Turn—1406

Frequently asked questions

Is GPT-5-Codex better than Grok 4.3?

Grok 4.3 is the stronger model overall, scoring 43.8 to 37.9 on the Noometry Index.

Which is cheaper, GPT-5-Codex or Grok 4.3?

Grok 4.3 is cheaper. It lists at $1.25 per million input tokens and $2.50 per million output tokens; GPT-5-Codex lists at $1.25 and $10.

Is GPT-5-Codex or Grok 4.3 better for coding?

They score almost the same on coding (42.4 vs 41.6); test both on your own repository before choosing.

Which has the bigger context window?

Grok 4.3 does, with 1M tokens against 400K.

How many benchmarks do GPT-5-Codex and Grok 4.3 share?

1 benchmark has published results for both models. GPT-5-Codex has 3 scored results on Noometry and Grok 4.3 has 40.

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