# GPT-5.3 Chat vs GPT-5-Codex

> GPT-5.3 Chat is the stronger model overall, scoring 42.1 to 37.3 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-5-3-chat-vs-gpt-5-codex
- Last updated: 2026-10-10
- Shared benchmarks: 0

## Summary

- GPT-5-Codex is cheaper at $1.25 / $10 per million input/output tokens, against $1.75 / $14 for GPT-5.3 Chat.
- GPT-5-Codex accepts more context: 400K tokens versus 128K.

## Snapshot

| | GPT-5.3 Chat | GPT-5-Codex |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Noometry Index | 42.1 | 37.3 |
| Rank | 109 | 190 |
| Context | 128K | 400K |
| Input $/M | $1.75 | $1.25 |
| Output $/M | $14 | $10 |
| Weights | Proprietary | Proprietary |

## Coding

- GPT-5.3 Chat: 40.8 (#124)
- GPT-5-Codex: 41.9 (#100)

| Benchmark | GPT-5.3 Chat | GPT-5-Codex |
|---|---|---|
| WeirdML | — | 54.5% |
| LMArena Coding | 1408 | — |

## Agentic & Tool Use

- GPT-5.3 Chat: —
- GPT-5-Codex: 30.8 (#66)

| Benchmark | GPT-5.3 Chat | GPT-5-Codex |
|---|---|---|
| Terminal-Bench | — | 44.3% |

## Reasoning

- GPT-5.3 Chat: 27.3 (#105)
- GPT-5-Codex: 30.0 (#80)

| Benchmark | GPT-5.3 Chat | GPT-5-Codex |
|---|---|---|
| Kagi LLM Benchmark | — | 70.3% |
| LMArena Hard Prompts | 1399 | — |

## Math

- GPT-5.3 Chat: 35.4 (#146)
- GPT-5-Codex: —

| Benchmark | GPT-5.3 Chat | GPT-5-Codex |
|---|---|---|
| LMArena Math | 1389 | — |

## Knowledge

- GPT-5.3 Chat: 38.2 (#137)
- GPT-5-Codex: —

| Benchmark | GPT-5.3 Chat | GPT-5-Codex |
|---|---|---|
| LMArena Expert | 1397 | — |

## Multilingual

- GPT-5.3 Chat: 50.5 (#119)
- GPT-5-Codex: —

| Benchmark | GPT-5.3 Chat | GPT-5-Codex |
|---|---|---|
| LMArena Non-English | 1383 | — |
| LMArena Chinese | 1433 | — |
| LMArena French | 1398 | — |
| LMArena German | 1384 | — |
| LMArena Japanese | 1351 | — |
| LMArena Korean | 1347 | — |
| LMArena Russian | 1400 | — |
| LMArena Spanish | 1371 | — |

## Instruction Following

- GPT-5.3 Chat: 73.0 (#124)
- GPT-5-Codex: —

| Benchmark | GPT-5.3 Chat | GPT-5-Codex |
|---|---|---|
| LMArena Instruction Following | 1378 | — |

## Long Context

- GPT-5.3 Chat: 42.6 (#115)
- GPT-5-Codex: —

| Benchmark | GPT-5.3 Chat | GPT-5-Codex |
|---|---|---|
| LMArena Longer Query | 1396 | — |

## Writing & Preference

- GPT-5.3 Chat: 63.3 (#65)
- GPT-5-Codex: —

| Benchmark | GPT-5.3 Chat | GPT-5-Codex |
|---|---|---|
| LMArena Text | 1389 | — |
| LMArena Creative Writing | 1356 | — |
| EQ-Bench Creative Writing | 1690 | — |
| LMArena Multi-Turn | 1413 | — |

## FAQ

### Is GPT-5.3 Chat better than GPT-5-Codex?

GPT-5.3 Chat is the stronger model overall, scoring 42.1 to 37.3 on the Noometry Index.

### Which is cheaper, GPT-5.3 Chat or GPT-5-Codex?

GPT-5-Codex is cheaper. It lists at $1.25 per million input tokens and $10 per million output tokens; GPT-5.3 Chat lists at $1.75 and $14.

### Is GPT-5.3 Chat or GPT-5-Codex better for coding?

GPT-5-Codex scores higher on coding benchmarks: 41.9 versus 40.8 in the Noometry coding category.

### Which has the bigger context window?

GPT-5-Codex does, with 400K tokens against 128K.

### How many benchmarks do GPT-5.3 Chat and GPT-5-Codex share?

0 benchmarks have published results for both models. GPT-5.3 Chat has 18 scored results on Noometry and GPT-5-Codex has 3.