# GPT-5-Codex vs Mistral Medium 3.5

> Mistral Medium 3.5 is the stronger model overall, scoring 39.6 to 37.3 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-5-codex-vs-mistral-medium-3-5
- Last updated: 2026-10-10
- Shared benchmarks: 1

## Summary

- They share 1 benchmark with published results for both. GPT-5-Codex scores higher in 2 categories and Mistral Medium 3.5 in 0 categories; 2 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where GPT-5-Codex leads 30.0 to 16.6.
- The biggest single-benchmark swing is Kagi LLM Benchmark: 70.3% for GPT-5-Codex and 41.4% for Mistral Medium 3.5.
- Mistral Medium 3.5 is cheaper at $1.50 / $7.50 per million input/output tokens, against $1.25 / $10 for GPT-5-Codex.
- GPT-5-Codex accepts more context: 400K tokens versus 262K.
- Mistral Medium 3.5 has downloadable open weights; the other is API-only.

## Snapshot

| | GPT-5-Codex | Mistral Medium 3.5 |
|---|---|---|
| Provider | OpenAI | Mistral AI |
| Noometry Index | 37.3 | 39.6 |
| Rank | 190 | 151 |
| Context | 400K | 262K |
| Input $/M | $1.25 | $1.50 |
| Output $/M | $10 | $7.50 |
| Weights | Proprietary | Open |

## Coding

- GPT-5-Codex: 41.9 (#100)
- Mistral Medium 3.5: 35.7 (#208)

| Benchmark | GPT-5-Codex | Mistral Medium 3.5 |
|---|---|---|
| LMArena WebDev | — | 1263 |
| WeirdML | 54.5% | — |
| LMArena Coding | — | 1461 |

## Agentic & Tool Use

- GPT-5-Codex: 30.8 (#66)
- Mistral Medium 3.5: —

| Benchmark | GPT-5-Codex | Mistral Medium 3.5 |
|---|---|---|
| Terminal-Bench | 44.3% | — |

## Reasoning

- GPT-5-Codex: 30.0 (#80)
- Mistral Medium 3.5: 16.6 (#290)

| Benchmark | GPT-5-Codex | Mistral Medium 3.5 |
|---|---|---|
| Kagi LLM Benchmark | 70.3% | 41.4% |
| NYT Connections (extended) | — | 12.9% |
| LMArena Hard Prompts | — | 1436 |
| Epoch Capabilities Index | — | 141.42 |

## Math

- GPT-5-Codex: —
- Mistral Medium 3.5: 36.4 (#113)

| Benchmark | GPT-5-Codex | Mistral Medium 3.5 |
|---|---|---|
| LMArena Math | — | 1432 |

## Knowledge

- GPT-5-Codex: —
- Mistral Medium 3.5: 39.3 (#123)

| Benchmark | GPT-5-Codex | Mistral Medium 3.5 |
|---|---|---|
| LMArena Expert | — | 1431 |

## Multimodal

- GPT-5-Codex: —
- Mistral Medium 3.5: 37.6 (#64)

| Benchmark | GPT-5-Codex | Mistral Medium 3.5 |
|---|---|---|
| LMArena Vision | — | 1222 |

## Multilingual

- GPT-5-Codex: —
- Mistral Medium 3.5: 52.1 (#93)

| Benchmark | GPT-5-Codex | Mistral Medium 3.5 |
|---|---|---|
| LMArena Non-English | — | 1405 |
| LMArena Chinese | — | 1443 |
| LMArena French | — | 1448 |
| LMArena German | — | 1453 |
| LMArena Korean | — | 1387 |
| LMArena Russian | — | 1396 |
| LMArena Spanish | — | 1406 |

## Instruction Following

- GPT-5-Codex: —
- Mistral Medium 3.5: 74.7 (#87)

| Benchmark | GPT-5-Codex | Mistral Medium 3.5 |
|---|---|---|
| LMArena Instruction Following | — | 1414 |

## Long Context

- GPT-5-Codex: —
- Mistral Medium 3.5: 43.2 (#101)

| Benchmark | GPT-5-Codex | Mistral Medium 3.5 |
|---|---|---|
| LMArena Longer Query | — | 1414 |

## Writing & Preference

- GPT-5-Codex: —
- Mistral Medium 3.5: 58.6 (#113)

| Benchmark | GPT-5-Codex | Mistral Medium 3.5 |
|---|---|---|
| LMArena Text | — | 1421 |
| LMArena Creative Writing | — | 1372 |
| EQ-Bench 4 | — | 993 |
| LMArena Multi-Turn | — | 1423 |

## FAQ

### Is GPT-5-Codex better than Mistral Medium 3.5?

Mistral Medium 3.5 is the stronger model overall, scoring 39.6 to 37.3 on the Noometry Index.

### Which is cheaper, GPT-5-Codex or Mistral Medium 3.5?

Mistral Medium 3.5 is cheaper. It lists at $1.50 per million input tokens and $7.50 per million output tokens; GPT-5-Codex lists at $1.25 and $10.

### Is GPT-5-Codex or Mistral Medium 3.5 better for coding?

GPT-5-Codex scores higher on coding benchmarks: 41.9 versus 35.7 in the Noometry coding category.

### Which has the bigger context window?

GPT-5-Codex does, with 400K tokens against 262K.

### How many benchmarks do GPT-5-Codex and Mistral Medium 3.5 share?

1 benchmark has published results for both models. GPT-5-Codex has 3 scored results on Noometry and Mistral Medium 3.5 has 22.