Noometry

Model comparison

GPT-5.3 Codex vs Llama 3.1-405B

GPT-5.3 Codex is the stronger model overall, scoring 45.8 to 30.7 on the Noometry Index.

Last verified . 2 shared benchmarks.

GPT-5.3 Codex OpenAI

45.8

Rank #69 Reported

Llama 3.1-405B Meta

30.7

Rank #288 Confirmed

Summary

  • They share 2 benchmarks with published results for both. GPT-5.3 Codex scores higher in 2 categories and Llama 3.1-405B in 0 categories; 2 gaps are clear of the uncertainty.
  • The widest gap is in agentic & tool use, where GPT-5.3 Codex leads 48.0 to 21.0.
  • The biggest single-benchmark swing is WeirdML: 79.3% for GPT-5.3 Codex and 21.4% for Llama 3.1-405B.
  • Llama 3.1-405B has downloadable open weights; the other is API-only.

Side by side

GPT-5.3 CodexLlama 3.1-405B
ProviderOpenAIMeta
Noometry Index45.830.7
Released2026-02-052024-07-23
WeightsProprietaryOpen
Context window400K—
Max output128K—
Input $ / M tokens$1.75—
Output $ / M tokens$14—
Results tracked842

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Category by category

Coding GPT-5.3 Codex leads

GPT-5.3 Codex: 48.6 (#56), Llama 3.1-405B: 33.1 (#262)

BenchmarkGPT-5.3 CodexLlama 3.1-405B
WeirdML79.3%21.4%
SWE-bench Verified74.8%—
LMArena WebDev1409—
LMArena Coding—1291
ALE-Bench1,655—

Agentic & Tool Use GPT-5.3 Codex leads

GPT-5.3 Codex: 48.0 (#9), Llama 3.1-405B: 21.0 (#140)

BenchmarkGPT-5.3 CodexLlama 3.1-405B
Terminal-Bench78.4%—
TheAgentCompany—7.4%
Cybench—7.5%
METR Time Horizons74.5%—
Vending-Bench 25,940—

Reasoning Not comparable

GPT-5.3 Codex: —, Llama 3.1-405B: 16.8 (#300)

BenchmarkGPT-5.3 CodexLlama 3.1-405B
Epoch Capabilities Index156.77128.75
SimpleBench—23%
Kagi LLM Benchmark—45%
LMArena Hard Prompts—1269
DTBench—61.4%
BIG-Bench Hard—82.9%
ForecastBench—59.9
HellaSwag—89.2%
PIQA—85.9%
WinoGrande—89.2%

Math Not comparable

GPT-5.3 Codex: —, Llama 3.1-405B: 18.4 (#290)

BenchmarkGPT-5.3 CodexLlama 3.1-405B
OTIS Mock AIME 2024-2025—9.7%
Omni-MATH—24.9%
LMArena Math—1281
MATH Level 5—49.8%

Knowledge Not comparable

GPT-5.3 Codex: —, Llama 3.1-405B: 30.4 (#227)

BenchmarkGPT-5.3 CodexLlama 3.1-405B
GPQA Diamond—50.9%
MMLU-Pro—72.3%
Confabulations—17.6%
GPQA (HELM)—52.2%
LMArena Expert—1243
ARC (AI2) Challenge—95.3%
MMLU—84.5%
TriviaQA—82.7%

Multilingual Not comparable

GPT-5.3 Codex: —, Llama 3.1-405B: 40.7 (#214)

BenchmarkGPT-5.3 CodexLlama 3.1-405B
LMArena Non-English—1248
LMArena Chinese—1242
LMArena French—1279
LMArena German—1252
LMArena Japanese—1208
LMArena Korean—1184
LMArena Russian—1265
LMArena Spanish—1260

Instruction Following Not comparable

GPT-5.3 Codex: —, Llama 3.1-405B: 65.9 (#214)

BenchmarkGPT-5.3 CodexLlama 3.1-405B
IFEval—81.1%
LMArena Instruction Following—1259

Long Context Not comparable

GPT-5.3 Codex: —, Llama 3.1-405B: 38.4 (#197)

BenchmarkGPT-5.3 CodexLlama 3.1-405B
LMArena Longer Query—1266

Writing & Preference Not comparable

GPT-5.3 Codex: —, Llama 3.1-405B: 38.9 (#251)

BenchmarkGPT-5.3 CodexLlama 3.1-405B
LMArena Text—1284
LMArena Creative Writing—1262
EQ-Bench Creative Writing—870
WildBench—78.3%
LMArena Multi-Turn—1297

Frequently asked questions

Is GPT-5.3 Codex better than Llama 3.1-405B?

GPT-5.3 Codex is the stronger model overall, scoring 45.8 to 30.7 on the Noometry Index.

Is GPT-5.3 Codex or Llama 3.1-405B better for coding?

GPT-5.3 Codex scores higher on coding benchmarks: 48.6 versus 33.1 in the Noometry coding category.

How many benchmarks do GPT-5.3 Codex and Llama 3.1-405B share?

2 benchmarks have published results for both models. GPT-5.3 Codex has 8 scored results on Noometry and Llama 3.1-405B has 42.

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