Noometry

Model comparison

GPT-5.3 Codex vs GPT-6 Luna

GPT-6 Luna is the stronger model overall, scoring 53.3 to 45.8 on the Noometry Index.

Last verified . 3 shared benchmarks.

GPT-5.3 Codex OpenAI

45.8

Rank #69 Reported

GPT-6 Luna OpenAI

53.3

Rank #36 Confirmed

Summary

  • They share 3 benchmarks with published results for both. GPT-5.3 Codex scores higher in 1 category and GPT-6 Luna in 1 category; 2 gaps are clear of the uncertainty.
  • The widest gap is in agentic & tool use, where GPT-5.3 Codex leads 48.0 to 33.3.
  • GPT-6 Luna is cheaper at $0.10 / $0.50 per million input/output tokens, against $1.75 / $14 for GPT-5.3 Codex.
  • GPT-6 Luna accepts more context: 1.05M tokens versus 400K.

Side by side

GPT-5.3 CodexGPT-6 Luna
ProviderOpenAIOpenAI
Noometry Index45.853.3
Released2026-02-052026-09-22
WeightsProprietaryProprietary
Context window400K1.05M
Max output128K128K
Input $ / M tokens$1.75$0.10
Output $ / M tokens$14$0.50
Results tracked842

Sponsored placements are available on pages like this one. Advertise on Noometry

Category by category

Coding GPT-6 Luna leads

GPT-5.3 Codex: 48.6 (#56), GPT-6 Luna: 55.5 (#25)

BenchmarkGPT-5.3 CodexGPT-6 Luna
LMArena WebDev14091581
ALE-Bench1,6551,577
SWE-bench Verified74.8%—
DeepSWE—66.6%
FrontierCode—42.4%
SciCode—54.6%
WeirdML79.3%—
LMArena Coding—1439

Agentic & Tool Use GPT-5.3 Codex leads

GPT-5.3 Codex: 48.0 (#9), GPT-6 Luna: 33.3 (#54)

BenchmarkGPT-5.3 CodexGPT-6 Luna
Terminal-Bench78.4%—
APEX-Agents—44.3%
GDP.pdf—23%
METR Time Horizons74.5%—
Vending-Bench 25,940—

Reasoning Not comparable

GPT-5.3 Codex: —, GPT-6 Luna: 48.2 (#41)

BenchmarkGPT-5.3 CodexGPT-6 Luna
Epoch Capabilities Index156.77156.28
ARC-AGI-2—59.3%
NYT Connections (extended)—68.7%
ARC-AGI-1—86.7%
CritPt—19.4%
Chess Puzzles—31%
LMArena Hard Prompts—1411
Mystery Game Puzzles—7%
DTBench—90.1%
LMCA—44.5%

Math Not comparable

GPT-5.3 Codex: —, GPT-6 Luna: 76.1 (#15)

BenchmarkGPT-5.3 CodexGPT-6 Luna
FrontierMath (Tiers 1-3)—78.9%
FrontierMath Tier 4—56.1%
OTIS Mock AIME 2024-2025—98.9%
ProofBench—64%
LMArena Math—1416

Knowledge Not comparable

GPT-5.3 Codex: —, GPT-6 Luna: 57.0 (#41)

BenchmarkGPT-5.3 CodexGPT-6 Luna
GPQA Diamond—90.5%
SimpleQA Verified—41.4%
LMArena Expert—1444

Multimodal Not comparable

GPT-5.3 Codex: —, GPT-6 Luna: 42.4 (#30)

BenchmarkGPT-5.3 CodexGPT-6 Luna
LMArena Vision—1217
Blueprint-Bench 2—31.2%
Furniture Assembly—44.2%

Multilingual Not comparable

GPT-5.3 Codex: —, GPT-6 Luna: 50.5 (#117)

BenchmarkGPT-5.3 CodexGPT-6 Luna
LMArena Non-English—1386
LMArena Chinese—1433
LMArena French—1420
LMArena German—1369
LMArena Japanese—1369
LMArena Korean—1360
LMArena Russian—1394
LMArena Spanish—1393

Instruction Following Not comparable

GPT-5.3 Codex: —, GPT-6 Luna: 74.3 (#99)

BenchmarkGPT-5.3 CodexGPT-6 Luna
LMArena Instruction Following—1409

Long Context Not comparable

GPT-5.3 Codex: —, GPT-6 Luna: 43.0 (#111)

BenchmarkGPT-5.3 CodexGPT-6 Luna
LMArena Longer Query—1409

Writing & Preference Not comparable

GPT-5.3 Codex: —, GPT-6 Luna: 58.3 (#119)

BenchmarkGPT-5.3 CodexGPT-6 Luna
LMArena Text—1391
LMArena Creative Writing—1363
LMArena Multi-Turn—1396

Frequently asked questions

Is GPT-5.3 Codex better than GPT-6 Luna?

GPT-6 Luna is the stronger model overall, scoring 53.3 to 45.8 on the Noometry Index.

Which is cheaper, GPT-5.3 Codex or GPT-6 Luna?

GPT-6 Luna is cheaper. It lists at $0.10 per million input tokens and $0.50 per million output tokens; GPT-5.3 Codex lists at $1.75 and $14.

Is GPT-5.3 Codex or GPT-6 Luna better for coding?

GPT-6 Luna scores higher on coding benchmarks: 55.5 versus 48.6 in the Noometry coding category.

Which has the bigger context window?

GPT-6 Luna does, with 1.05M tokens against 400K.

How many benchmarks do GPT-5.3 Codex and GPT-6 Luna share?

3 benchmarks have published results for both models. GPT-5.3 Codex has 8 scored results on Noometry and GPT-6 Luna has 42.

Related comparisons

Go deeper