# GPT-5-Codex vs GPT-6 Luna

> GPT-6 Luna is the stronger model overall, scoring 53.3 to 37.9 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-5-codex-vs-gpt-6-luna
- Last updated: 2026-10-11
- Shared benchmarks: 0

## Summary

- The widest gap is in reasoning, where GPT-6 Luna leads 48.2 to 30.9.
- GPT-6 Luna is cheaper at $0.10 / $0.50 per million input/output tokens, against $1.25 / $10 for GPT-5-Codex.
- GPT-6 Luna accepts more context: 1.05M tokens versus 400K.

## Snapshot

| | GPT-5-Codex | GPT-6 Luna |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Noometry Index | 37.9 | 53.3 |
| Rank | 192 | 36 |
| Context | 400K | 1.05M |
| Input $/M | $1.25 | $0.10 |
| Output $/M | $10 | $0.50 |
| Weights | Proprietary | Proprietary |

## Coding

- GPT-5-Codex: 42.4 (#103)
- GPT-6 Luna: 55.5 (#25)

| Benchmark | GPT-5-Codex | GPT-6 Luna |
|---|---|---|
| DeepSWE | — | 66.6% |
| FrontierCode | — | 42.4% |
| LMArena WebDev | — | 1581 |
| SciCode | — | 54.6% |
| WeirdML | 54.5% | — |
| LMArena Coding | — | 1439 |
| ALE-Bench | — | 1,577 |

## Agentic & Tool Use

- GPT-5-Codex: 31.0 (#72)
- GPT-6 Luna: 33.3 (#54)

| Benchmark | GPT-5-Codex | GPT-6 Luna |
|---|---|---|
| Terminal-Bench | 44.3% | — |
| APEX-Agents | — | 44.3% |
| GDP.pdf | — | 23% |

## Reasoning

- GPT-5-Codex: 30.9 (#83)
- GPT-6 Luna: 48.2 (#41)

| Benchmark | GPT-5-Codex | GPT-6 Luna |
|---|---|---|
| ARC-AGI-2 | — | 59.3% |
| Kagi LLM Benchmark | 70.3% | — |
| 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% |
| Epoch Capabilities Index | — | 156.28 |

## Math

- GPT-5-Codex: —
- GPT-6 Luna: 76.1 (#15)

| Benchmark | GPT-5-Codex | GPT-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

- GPT-5-Codex: —
- GPT-6 Luna: 57.0 (#41)

| Benchmark | GPT-5-Codex | GPT-6 Luna |
|---|---|---|
| GPQA Diamond | — | 90.5% |
| SimpleQA Verified | — | 41.4% |
| LMArena Expert | — | 1444 |

## Multimodal

- GPT-5-Codex: —
- GPT-6 Luna: 42.4 (#30)

| Benchmark | GPT-5-Codex | GPT-6 Luna |
|---|---|---|
| LMArena Vision | — | 1217 |
| Blueprint-Bench 2 | — | 31.2% |
| Furniture Assembly | — | 44.2% |

## Multilingual

- GPT-5-Codex: —
- GPT-6 Luna: 50.5 (#117)

| Benchmark | GPT-5-Codex | GPT-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

- GPT-5-Codex: —
- GPT-6 Luna: 74.3 (#99)

| Benchmark | GPT-5-Codex | GPT-6 Luna |
|---|---|---|
| LMArena Instruction Following | — | 1409 |

## Long Context

- GPT-5-Codex: —
- GPT-6 Luna: 43.0 (#111)

| Benchmark | GPT-5-Codex | GPT-6 Luna |
|---|---|---|
| LMArena Longer Query | — | 1409 |

## Writing & Preference

- GPT-5-Codex: —
- GPT-6 Luna: 58.3 (#119)

| Benchmark | GPT-5-Codex | GPT-6 Luna |
|---|---|---|
| LMArena Text | — | 1391 |
| LMArena Creative Writing | — | 1363 |
| LMArena Multi-Turn | — | 1396 |

## FAQ

### Is GPT-5-Codex better than GPT-6 Luna?

GPT-6 Luna is the stronger model overall, scoring 53.3 to 37.9 on the Noometry Index.

### Which is cheaper, GPT-5-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-Codex lists at $1.25 and $10.

### Is GPT-5-Codex or GPT-6 Luna better for coding?

GPT-6 Luna scores higher on coding benchmarks: 55.5 versus 42.4 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-Codex and GPT-6 Luna share?

0 benchmarks have published results for both models. GPT-5-Codex has 3 scored results on Noometry and GPT-6 Luna has 42.