# Mistral Medium 3.5 128B vs o3-mini

> Side-by-side benchmark comparison for Mistral Medium 3.5 128B and o3-mini across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/mistral-medium-3-5-128b-vs-o3-mini
- Last updated: September 10, 2026

- Shared sourced benchmarks: 1
- HTML indexing: indexable
- Ranking lane: BenchAlign v5

## Quick Verdict

Evidence is too thin for a benchmark verdict: Mistral Medium 3.5 128B and o3-mini share only 1 sourced benchmark row.

## Summary

- Only 1 shared sourced benchmark row is available. That is not enough for a broad capability verdict, so this mirror does not name an overall winner.
- o3-mini has the lower published output-token price.
- Mistral Medium 3.5 128B has the larger published context window at 256K.

## Model Snapshot

| Property | Mistral Medium 3.5 128B | o3-mini |
|----------|----------|----------|
| Creator | Mistral | OpenAI |
| Type | Open Weight | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 256K | 200K |
| Independent public score (not head-to-head) | 30.13 | 46.83 |
| Benchmarks Covered | 7 | 5 |
| Pricing (input/output) | $1.50 / $7.50 | $1.10 / $4.40 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Mistral Medium 3.5 128B public-lane score: 21.9 (Supported · #150/152)
- o3-mini public-lane score: Coming soon

| Benchmark | Mistral Medium 3.5 128B | o3-mini | Winner |
|-----------|-----------|-----------|--------|
| τ³-bench results | 91.4% | Coming soon | Coming soon |
| Gert Labs | 39.10% | Coming soon | Coming soon |
| Terminal-Bench 2.1 (Vals) | 39.0% | Coming soon | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- Mistral Medium 3.5 128B public-lane score: 36.9 (Estimated · #127/151)
- o3-mini public-lane score: 45.3 (Estimated · #88/151)

| Benchmark | Mistral Medium 3.5 128B | o3-mini | Winner |
|-----------|-----------|-----------|--------|
| SWE-bench Verified | 77.6% | 49.3% | Mistral Medium 3.5 128B |
| SWE-bench (Vals) | 66.4% | Coming soon | Coming soon |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- Mistral Medium 3.5 128B public-lane score: 55.6 (Unranked · 1 rankable row)
- o3-mini public-lane score: Coming soon

### Reasoning

- Winner: Insufficient shared evidence
- Mistral Medium 3.5 128B public-lane score: 68.6 (Unranked · 2 rankable rows)
- o3-mini public-lane score: Coming soon

### Knowledge

- Winner: Insufficient shared evidence
- Mistral Medium 3.5 128B public-lane score: 39 (Supported · #140/183)
- o3-mini public-lane score: 39.7 (Supported · #134/183)

| Benchmark | Mistral Medium 3.5 128B | o3-mini | Winner |
|-----------|-----------|-----------|--------|
| GPQA Diamond (Vals) | 34.8% | Coming soon | Coming soon |
| MMLU-Pro (Vals) | 75.3% | Coming soon | Coming soon |
| MMLU | Coming soon | 86.9% | Coming soon |
| GPQA | Coming soon | 77.2% | Coming soon |

### Instruction Following

- Winner: Insufficient shared evidence
- Mistral Medium 3.5 128B public-lane score: 84 (#48/123)
- o3-mini public-lane score: Coming soon

| Benchmark | Mistral Medium 3.5 128B | o3-mini | Winner |
|-----------|-----------|-----------|--------|
| IFEval | Coming soon | 93.9% | Coming soon |

### Mathematics

- Winner: Insufficient shared evidence
- Mistral Medium 3.5 128B public-lane score: Coming soon
- o3-mini public-lane score: Coming soon

| Benchmark | Mistral Medium 3.5 128B | o3-mini | Winner |
|-----------|-----------|-----------|--------|
| AIME 2024 | Coming soon | 87.3% | Coming soon |

## FAQ

### Is there enough evidence to pick between Mistral Medium 3.5 128B and o3-mini?

Not yet. The models share only 1 sourced benchmark row, so this mirror reports the available measurements and metadata without naming a broad winner.

### What can I compare safely on this page?

Published pricing, context windows, model type, and individual shared benchmark rows are directly comparable. Independent overall scores and non-overlapping benchmark coverage are labeled separately and should not be read as a controlled head-to-head result.

## Related Comparisons

- [Mistral Medium 3.5 128B vs o3](/compare/mistral-medium-3-5-128b-vs-o3)
- [o3-mini vs o3](/compare/o3-vs-o3-mini)
- [Mistral Medium 3.5 128B vs o3-pro](/compare/mistral-medium-3-5-128b-vs-o3-pro)
- [o3-mini vs o3-pro](/compare/o3-mini-vs-o3-pro)

## Explore More

- [Mistral Medium 3.5 128B profile](/models/mistral-medium-3-5-128b)
- [o3-mini profile](/models/o3-mini)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)