# Gemini 3.1 Pro vs Mistral Medium 3.5 128B

> Side-by-side benchmark comparison for Gemini 3.1 Pro and Mistral Medium 3.5 128B across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gemini-3-1-pro-vs-mistral-medium-3-5-128b
- Last updated: September 18, 2026

- Shared sourced benchmarks: 5
- HTML indexing: indexable
- Ranking lane: BenchAlign v5

## Quick Verdict

Pick Gemini 3.1 Pro if you want the stronger benchmark profile. Mistral Medium 3.5 128B only makes more sense when its price, context window, or workload-specific category wins matter more than the overall score.

## Summary

- Gemini 3.1 Pro leads overall 70.18 to 42.64.
- The clearest category separation is in knowledge, where the averages are 66.1 for Gemini 3.1 Pro and 40.7 for Mistral Medium 3.5 128B.
- The biggest single benchmark swing is GPQA Diamond (Vals) in Knowledge, with scores of 95.5% and 34.8%.
- Mistral Medium 3.5 128B is the cheaper option on output tokens, which matters if you expect large responses or heavy interactive use.
- Gemini 3.1 Pro also has the larger context window at 1M.

## Model Snapshot

| Property | Gemini 3.1 Pro | Mistral Medium 3.5 128B |
|----------|----------|----------|
| Creator | Google | Mistral |
| Type | Proprietary | Open Weight |
| Reasoning | Reasoning | Reasoning |
| Context | 1M | 256K |
| Overall Score | 70.18 | 42.64 |
| Benchmarks Covered | 28 | 7 |
| Pricing (input/output) | $2.00 / $12.00 | $1.50 / $7.50 |

## Category Breakdown

### Agentic

- Winner: Gemini 3.1 Pro
- Gemini 3.1 Pro public-lane score: 39.9 (Supported · #121/154)
- Mistral Medium 3.5 128B public-lane score: 22.1 (Supported · #152/154)

| Benchmark | Gemini 3.1 Pro | Mistral Medium 3.5 128B | Winner |
|-----------|-----------|-----------|--------|
| Claw-Eval | 57.8% | Coming soon | Coming soon |
| DeepSearchQA | 69.7% | Coming soon | Coming soon |
| τ²-bench results | 95.6% | Coming soon | Coming soon |
| Gert Labs | 56.87% | 39.10% | Gemini 3.1 Pro |
| ResearchClawBench | 13.3% | Coming soon | Coming soon |
| Terminal-Bench 2.1 (Vals) | 70.8% | 39.0% | Gemini 3.1 Pro |
| τ³-bench results | Coming soon | 91.4% | Coming soon |

### Coding

- Winner: Coming soon
- Gemini 3.1 Pro public-lane score: 45.9 (Supported · #89/154)
- Mistral Medium 3.5 128B public-lane score: 39.2 (Estimated · #125/154)

| Benchmark | Gemini 3.1 Pro | Mistral Medium 3.5 128B | Winner |
|-----------|-----------|-----------|--------|
| LiveCodeBench Pro | 82.9% | Coming soon | Coming soon |
| React Native Evals | 78.9% | Coming soon | Coming soon |
| Vibe Code Bench | 32.03% | Coming soon | Coming soon |
| LiveCodeBench (Vals) | 88.5% | Coming soon | Coming soon |
| SWE-bench (Vals) | 78.8% | 66.4% | Gemini 3.1 Pro |
| SWE-bench Verified | Coming soon | 77.6% | Coming soon |

### Reasoning

- Winner: Coming soon
- Gemini 3.1 Pro public-lane score: 50.7 (Unranked · 2 rankable rows)
- Mistral Medium 3.5 128B public-lane score: 68.6 (Unranked · 2 rankable rows)

| Benchmark | Gemini 3.1 Pro | Mistral Medium 3.5 128B | Winner |
|-----------|-----------|-----------|--------|
| ARC-AGI-2 | 77.1% | Coming soon | Coming soon |
| ARC-AGI-3 | 0.4% | Coming soon | Coming soon |

### Multimodal & Grounded

- Winner: Coming soon
- Gemini 3.1 Pro public-lane score: 79.1 (#12/49)
- Mistral Medium 3.5 128B public-lane score: 55.7 (Unranked · 1 rankable row)

| Benchmark | Gemini 3.1 Pro | Mistral Medium 3.5 128B | Winner |
|-----------|-----------|-----------|--------|
| MMMU-Pro | 83.9% | Coming soon | Coming soon |
| CharXiv | 80.2% | Coming soon | Coming soon |
| ERQA | 69.4% | Coming soon | Coming soon |
| SimpleVQA | 72.4% | Coming soon | Coming soon |
| ScreenSpot Pro | 84.4% | Coming soon | Coming soon |
| ZeroBench | 29.0% | Coming soon | Coming soon |
| MedXpertQA (MM) | 81.3% | Coming soon | Coming soon |

### Knowledge

- Winner: Gemini 3.1 Pro
- Gemini 3.1 Pro public-lane score: 66.1 (Supported · #22/184)
- Mistral Medium 3.5 128B public-lane score: 40.7 (Supported · #133/184)

| Benchmark | Gemini 3.1 Pro | Mistral Medium 3.5 128B | Winner |
|-----------|-----------|-----------|--------|
| GPQA-D | 94.3% | Coming soon | Coming soon |
| HLE w/o tools | 45.4% | Coming soon | Coming soon |
| HealthBench Hard | 20.6% | Coming soon | Coming soon |
| MedXpertQA (Text) | 71.5% | Coming soon | Coming soon |
| GPQA Diamond (Vals) | 95.5% | 34.8% | Gemini 3.1 Pro |
| MMLU-Pro (Vals) | 91.0% | 75.3% | Gemini 3.1 Pro |

### Instruction Following

- Winner: Coming soon
- Gemini 3.1 Pro public-lane score: Coming soon
- Mistral Medium 3.5 128B public-lane score: 82.6 (#48/124)

### Mathematics

- Winner: Coming soon
- Gemini 3.1 Pro public-lane score: 54.2 (Unranked · 2 rankable rows)
- Mistral Medium 3.5 128B public-lane score: Coming soon

| Benchmark | Gemini 3.1 Pro | Mistral Medium 3.5 128B | Winner |
|-----------|-----------|-----------|--------|
| FrontierMath v2 (Tiers 1-3) | 36.900% | Coming soon | Coming soon |
| FrontierMath v2 (Tier 4) | 16.700% | Coming soon | Coming soon |

## FAQ

### Which is better overall, Gemini 3.1 Pro or Mistral Medium 3.5 128B?

Gemini 3.1 Pro is ahead overall on BenchLM right now.

### Where is the biggest gap between Gemini 3.1 Pro and Mistral Medium 3.5 128B?

The widest category gap is in knowledge, where the averages are 66.1 for Gemini 3.1 Pro and 40.7 for Mistral Medium 3.5 128B.

### How many benchmarks does Gemini 3.1 Pro cover on BenchLM?

Gemini 3.1 Pro currently has 28 sourced benchmark scores on BenchLM.

### How many benchmarks does Mistral Medium 3.5 128B cover on BenchLM?

Mistral Medium 3.5 128B currently has 7 sourced benchmark scores on BenchLM.

## Related Comparisons

- [Gemini 3.1 Pro vs Claude Fable 5.1](/compare/claude-fable-5-1-vs-gemini-3-1-pro)
- [Mistral Medium 3.5 128B vs Claude Fable 5.1](/compare/claude-fable-5-1-vs-mistral-medium-3-5-128b)
- [Gemini 3.1 Pro vs GPT-6 Astra](/compare/gemini-3-1-pro-vs-gpt-6-astra)
- [Mistral Medium 3.5 128B vs GPT-6 Astra](/compare/gpt-6-astra-vs-mistral-medium-3-5-128b)

## Explore More

- [Gemini 3.1 Pro profile](/models/gemini-3-1-pro)
- [Mistral Medium 3.5 128B profile](/models/mistral-medium-3-5-128b)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)