# Mistral Medium 3.5 vs o3

> o3 is the stronger model overall, scoring 47.5 to 40.2 on the Noometry Index.

- Canonical page: https://noometry.com/compare/mistral-medium-3-5-vs-o3
- Last updated: 2026-10-12
- Shared benchmarks: 19

## Summary

- They share 19 benchmarks with published results for both. Mistral Medium 3.5 scores higher in 2 categories and o3 in 7 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where o3 leads 32.0 to 17.3.
- The biggest single-benchmark swing is Kagi LLM Benchmark: 41.4% for Mistral Medium 3.5 and 67.6% for o3.
- Mistral Medium 3.5 is cheaper at $1.50 / $7.50 per million input/output tokens, against $2 / $8 for o3.
- Mistral Medium 3.5 accepts more context: 262K tokens versus 200K.
- Mistral Medium 3.5 has downloadable open weights; the other is API-only.

## Snapshot

| | Mistral Medium 3.5 | o3 |
|---|---|---|
| Provider | Mistral AI | OpenAI |
| Noometry Index | 40.2 | 47.5 |
| Rank | 152 | 61 |
| Context | 262K | 200K |
| Input $/M | $1.50 | $2 |
| Output $/M | $7.50 | $8 |
| Weights | Open | Proprietary |

## Coding

- Mistral Medium 3.5: 36.0 (#213)
- o3: 46.8 (#64)

| Benchmark | Mistral Medium 3.5 | o3 |
|---|---|---|
| LMArena Coding | 1461 | 1408 |
| SWE-bench Verified | — | 62.3% |
| SWE-bench Verified (bash only) | — | 58.4% |
| Aider Polyglot | — | 81.3% |
| LMArena WebDev | 1264 | — |
| GSO | — | 8.8% |
| WeirdML | — | 52.4% |
| CadEval | — | 74% |
| ALE-Bench | — | 933.55 |

## Agentic & Tool Use

- Mistral Medium 3.5: —
- o3: 34.5 (#44)

| Benchmark | Mistral Medium 3.5 | o3 |
|---|---|---|
| Berkeley Function Calling Leaderboard | — | 63% |
| GDPval | — | 30.8% |
| DeepResearch Bench | — | 45.2% |
| OSWorld | — | 23% |
| LMArena Search | — | 1144 |
| METR Time Horizons | — | 65.4% |

## Reasoning

- Mistral Medium 3.5: 17.3 (#295)
- o3: 32.0 (#78)

| Benchmark | Mistral Medium 3.5 | o3 |
|---|---|---|
| Kagi LLM Benchmark | 41.4% | 67.6% |
| LMArena Hard Prompts | 1436 | 1402 |
| Epoch Capabilities Index | 141.35 | 146.86 |
| ARC-AGI-2 | — | 6.5% |
| SimpleBench | — | 53.1% |
| NYT Connections (extended) | 12.9% | — |
| ARC-AGI-1 | — | 60.8% |
| CritPt | — | 1.4% |
| Chess Puzzles | — | 38% |
| EnigmaEval | — | 13.1% |
| Mystery Game Puzzles | — | 29% |
| DTBench | — | 84.8% |
| LMCA | — | 39.7% |
| ForecastBench | — | 62.5 |

## Math

- Mistral Medium 3.5: 39.1 (#113)
- o3: 50.2 (#58)

| Benchmark | Mistral Medium 3.5 | o3 |
|---|---|---|
| LMArena Math | 1431 | 1426 |
| FrontierMath (Tiers 1-3) | — | 33.3% |
| OTIS Mock AIME 2024-2025 | — | 84.4% |
| Omni-MATH | — | 71.4% |
| MATH Level 5 | — | 97.8% |
| FrontierMath (Feb 2025 set) | — | 18.7% |
| FrontierMath Tier 4 (v1) | — | 2.1% |

## Knowledge

- Mistral Medium 3.5: 40.0 (#126)
- o3: 54.6 (#52)

| Benchmark | Mistral Medium 3.5 | o3 |
|---|---|---|
| LMArena Expert | 1432 | 1402 |
| GPQA Diamond | — | 81.8% |
| Humanity's Last Exam | — | 20.3% |
| SimpleQA Verified | — | 49.4% |
| MMLU-Pro | — | 85.9% |
| Confabulations | — | 14.4% |
| GPQA (HELM) | — | 75.3% |

## Multimodal

- Mistral Medium 3.5: 38.3 (#65)
- o3: 41.4 (#36)

| Benchmark | Mistral Medium 3.5 | o3 |
|---|---|---|
| LMArena Vision | 1223 | 1214 |
| GeoBench | — | 74% |
| VPCT | — | 52% |

## Multilingual

- Mistral Medium 3.5: 51.9 (#100)
- o3: 51.7 (#105)

| Benchmark | Mistral Medium 3.5 | o3 |
|---|---|---|
| LMArena Non-English | 1404 | 1401 |
| LMArena Chinese | 1442 | 1437 |
| LMArena French | 1448 | 1430 |
| LMArena German | 1451 | 1420 |
| LMArena Korean | 1385 | 1370 |
| LMArena Russian | 1395 | 1406 |
| LMArena Spanish | 1409 | 1395 |
| LMArena Japanese | — | 1403 |

## Instruction Following

- Mistral Medium 3.5: 74.6 (#90)
- o3: 72.8 (#127)

| Benchmark | Mistral Medium 3.5 | o3 |
|---|---|---|
| LMArena Instruction Following | 1415 | 1368 |
| IFEval | — | 86.9% |

## Long Context

- Mistral Medium 3.5: 43.2 (#103)
- o3: 53.3 (#6)

| Benchmark | Mistral Medium 3.5 | o3 |
|---|---|---|
| LMArena Longer Query | 1415 | 1372 |
| Fiction.LiveBench | — | 88.9% |
| CL-bench | — | 17.8% |

## Writing & Preference

- Mistral Medium 3.5: 58.5 (#117)
- o3: 63.5 (#64)

| Benchmark | Mistral Medium 3.5 | o3 |
|---|---|---|
| LMArena Text | 1421 | 1410 |
| LMArena Creative Writing | 1374 | 1359 |
| LMArena Multi-Turn | 1423 | 1405 |
| Short-Story Creative Writing | — | 83.9% |
| EQ-Bench Creative Writing | — | 1676 |
| WildBench | — | 86.1% |
| EQ-Bench 4 | 993 | — |

## FAQ

### Is Mistral Medium 3.5 better than o3?

o3 is the stronger model overall, scoring 47.5 to 40.2 on the Noometry Index.

### Which is cheaper, Mistral Medium 3.5 or o3?

Mistral Medium 3.5 is cheaper. It lists at $1.50 per million input tokens and $7.50 per million output tokens; o3 lists at $2 and $8.

### Is Mistral Medium 3.5 or o3 better for coding?

o3 scores higher on coding benchmarks: 46.8 versus 36.0 in the Noometry coding category.

### Which has the bigger context window?

Mistral Medium 3.5 does, with 262K tokens against 200K.

### How many benchmarks do Mistral Medium 3.5 and o3 share?

19 benchmarks have published results for both models. Mistral Medium 3.5 has 22 scored results on Noometry and o3 has 63.