# GPT-5.6 Terra vs Mistral Medium 3.5 128B

> Side-by-side benchmark comparison for GPT-5.6 Terra and Mistral Medium 3.5 128B across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gpt-5-6-terra-vs-mistral-medium-3-5-128b
- Last updated: September 24, 2026

- Shared sourced benchmarks: 4
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.7

## Quick Verdict

Pick GPT-5.6 Terra 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

- GPT-5.6 Terra leads overall 72.58 to 36.05.
- The clearest category separation is in agentic, where the averages are 59.5 for GPT-5.6 Terra and 20.1 for Mistral Medium 3.5 128B.
- The biggest single benchmark swing is GPQA Diamond (Vals) in Knowledge, with scores of 90.9% 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.
- GPT-5.6 Terra also has the larger context window at 1.05M.

## Model Snapshot

| Property | GPT-5.6 Terra | Mistral Medium 3.5 128B |
|----------|----------|----------|
| Creator | OpenAI | Mistral |
| Type | Proprietary | Open Weight |
| Reasoning | Reasoning | Reasoning |
| Context | 1.05M | 256K |
| Overall Score | 72.58 | 36.05 |
| Benchmarks Covered | 32 | 7 |
| Pricing (input/output) | $2.00 / $12.00 | $1.50 / $7.50 |

## Category Breakdown

### Agentic

- Winner: GPT-5.6 Terra
- GPT-5.6 Terra public-lane score: 59.5 (Supported · #18/105)
- Mistral Medium 3.5 128B public-lane score: 20.1 (Supported · #86/105)

| Benchmark | GPT-5.6 Terra | Mistral Medium 3.5 128B | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 3.0 | 20.8% | Coming soon | Coming soon |
| Terminal-Bench 2.1 | 87.4% | Coming soon | Coming soon |
| BrowseComp | 87.5% | Coming soon | Coming soon |
| OSWorld 2.0 | 50.2% | Coming soon | Coming soon |
| CyberGym | 81.8% | Coming soon | Coming soon |
| ExploitGym | 23.2% | Coming soon | Coming soon |
| Toolathlon | 53.1% | Coming soon | Coming soon |
| Terminal-Bench 2.1 (Vals) | 77.5% | 39.0% | GPT-5.6 Terra |
| ApprenticeBench | 16% | Coming soon | Coming soon |
| τ³-bench results | Coming soon | 91.4% | Coming soon |
| Gert Labs | Coming soon | 39.10% | Coming soon |

### Coding

- Winner: Directional only
- GPT-5.6 Terra public-lane score: 64.7 (Supported · #8/135)
- Mistral Medium 3.5 128B public-lane score: 26.9 (Estimated · #94/135)

| Benchmark | GPT-5.6 Terra | Mistral Medium 3.5 128B | Winner |
|-----------|-----------|-----------|--------|
| SWE-bench Pro | 63.4% | Coming soon | Coming soon |
| Terminal-Bench 2.1 | 87.4% | Coming soon | Coming soon |
| DeepSWE | 69.6% | Coming soon | Coming soon |
| FrontierCode 1.1 Extended | 55.8% | Coming soon | Coming soon |
| cursorBench32 | 64.9% | Coming soon | Coming soon |
| VulcanBench v3 | 87.0% | Coming soon | Coming soon |
| LiveCodeBench (Vals) | 85.9% | Coming soon | Coming soon |
| SWE-bench (Vals) | 95.4% | 66.4% | GPT-5.6 Terra |
| SWE-bench Verified | Coming soon | 77.6% | Coming soon |

### Reasoning

- Winner: Not comparable
- GPT-5.6 Terra public-lane score: 65.4 (#12/19)
- Mistral Medium 3.5 128B public-lane score: 69.7 (Unranked · 2 rankable rows)

| Benchmark | GPT-5.6 Terra | Mistral Medium 3.5 128B | Winner |
|-----------|-----------|-----------|--------|
| ARC-AGI-2 | 83.9% | Coming soon | Coming soon |
| ARC-AGI-3 | 0.8% | Coming soon | Coming soon |

### Multimodal & Grounded

- Winner: Not comparable
- GPT-5.6 Terra public-lane score: 77.2 (#16/50)
- Mistral Medium 3.5 128B public-lane score: 55.7 (Unranked · 1 rankable row)

| Benchmark | GPT-5.6 Terra | Mistral Medium 3.5 128B | Winner |
|-----------|-----------|-----------|--------|
| MMMU-Pro | 80.7% | Coming soon | Coming soon |
| MMMU-Pro w/ Python | 82% | Coming soon | Coming soon |

### Knowledge

- Winner: GPT-5.6 Terra
- GPT-5.6 Terra public-lane score: 71.1 (Supported · #9/158)
- Mistral Medium 3.5 128B public-lane score: 32.1 (Supported · #120/158)

| Benchmark | GPT-5.6 Terra | Mistral Medium 3.5 128B | Winner |
|-----------|-----------|-----------|--------|
| GPQA | 92.9% | Coming soon | Coming soon |
| GPQA-D | 92.9% | Coming soon | Coming soon |
| HLE-Verified | 51.1% | Coming soon | Coming soon |
| LABBench2 | 81.2% | Coming soon | Coming soon |
| HealthBench Professional | 57.7% | Coming soon | Coming soon |
| HealthBench Hard | 32.7% | Coming soon | Coming soon |
| GPQA Diamond (Vals) | 90.9% | 34.8% | GPT-5.6 Terra |
| MMLU-Pro (Vals) | 86.7% | 75.3% | GPT-5.6 Terra |

### Instruction Following

- Winner: Directional only
- GPT-5.6 Terra public-lane score: 85.7 (#35/124)
- Mistral Medium 3.5 128B public-lane score: 82.6 (#49/124)

### Mathematics

- Winner: Not comparable
- GPT-5.6 Terra public-lane score: 96.8 (Unranked · 3 rankable rows)
- Mistral Medium 3.5 128B public-lane score: Coming soon

| Benchmark | GPT-5.6 Terra | Mistral Medium 3.5 128B | Winner |
|-----------|-----------|-----------|--------|
| FrontierMath (legacy) | 84.9% | Coming soon | Coming soon |
| FrontierMath v2 (Tiers 1-3) | 84.900% | Coming soon | Coming soon |
| FrontierMath v2 (Tier 4) | 68.300% | Coming soon | Coming soon |

## FAQ

### Which is better overall, GPT-5.6 Terra or Mistral Medium 3.5 128B?

GPT-5.6 Terra is ahead overall on BenchLM right now.

### Where is the biggest gap between GPT-5.6 Terra and Mistral Medium 3.5 128B?

The widest category gap is in agentic, where the averages are 59.5 for GPT-5.6 Terra and 20.1 for Mistral Medium 3.5 128B.

### How many benchmarks does GPT-5.6 Terra cover on BenchLM?

GPT-5.6 Terra currently has 32 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

- [GPT-5.6 Terra vs GPT-5.6 Sol](/compare/gpt-5-6-sol-vs-gpt-5-6-terra)
- [Mistral Medium 3.5 128B vs GPT-5.6 Sol](/compare/gpt-5-6-sol-vs-mistral-medium-3-5-128b)
- [GPT-5.6 Terra vs GPT-5.6 Luna](/compare/gpt-5-6-luna-vs-gpt-5-6-terra)
- [Mistral Medium 3.5 128B vs GPT-5.6 Luna](/compare/gpt-5-6-luna-vs-mistral-medium-3-5-128b)

## Explore More

- [GPT-5.6 Terra profile](/models/gpt-5-6-terra)
- [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)