# Mellum2.1-12B-A2.5B-Thinking vs Qwen3.5 397B

> Side-by-side benchmark comparison for Mellum2.1-12B-A2.5B-Thinking and Qwen3.5 397B across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/mellum2-1-12b-a2-5b-thinking-vs-qwen3-5-397b
- Last updated: October 8, 2026

- Shared sourced benchmarks: 5
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.8

## Quick Verdict

Qwen3.5 397B leads by point estimate. Conditional score ranges do not establish rank confidence. Choose using the category evidence and your own workload tests.

## Summary

- Qwen3.5 397B has the higher overall point estimate 53.89 to 37. Conditional score ranges do not establish rank confidence.
- The biggest single benchmark swing is SWE-bench Verified in Coding, with scores of 47% and 76.2%.
- Mellum2.1-12B-A2.5B-Thinking is the cheaper option on output tokens, which matters if you expect large responses or heavy interactive use.

## Model Snapshot

| Property | Mellum2.1-12B-A2.5B-Thinking | Qwen3.5 397B |
|----------|----------|----------|
| Creator | JetBrains | Alibaba |
| Type | Open Weight | Open Weight |
| Reasoning | Reasoning | Non-Reasoning |
| Context | 128K | 128K |
| Overall Score | null | 53.89 |
| Benchmarks Covered | 7 | 38 |
| Pricing (input/output) | $0.00 / $0.00 | $0.60 / $3.60 |

## Category Breakdown

### Agentic

- Winner: Not comparable
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Qwen3.5 397B public-lane score: 40 (Estimated · #62/122)

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Qwen3.5 397B | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 2.1 | 17.4% | Coming soon | Coming soon |
| Terminal-Bench 2.0 | Coming soon | 52.5% | Coming soon |
| BrowseComp | Coming soon | 62% | Coming soon |
| Claw-Eval | Coming soon | 56.8% | Coming soon |
| QwenClawBench | Coming soon | 51.8% | Coming soon |
| τ³-bench results | Coming soon | 68.4% | Coming soon |
| VITA-Bench | Coming soon | 43.7% | Coming soon |
| DeepPlanning | Coming soon | 37.6% | Coming soon |
| Toolathlon | Coming soon | 36.3% | Coming soon |
| MCP Atlas | Coming soon | 46.1% | Coming soon |
| MCP-Tasks | Coming soon | 74.2% | Coming soon |
| WideResearch | Coming soon | 74.0% | Coming soon |
| Gert Labs | Coming soon | 46.76% | Coming soon |
| ResearchClawBench | Coming soon | 14.2% | Coming soon |

### Coding

- Winner: Not comparable
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Qwen3.5 397B public-lane score: Coming soon

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Qwen3.5 397B | Winner |
|-----------|-----------|-----------|--------|
| LiveCodeBench v6 | 82.0% | 83.6% | Qwen3.5 397B |
| SWE-bench Verified | 47% | 76.2% | Qwen3.5 397B |
| SWE-bench Pro | 28% | 50.9% | Qwen3.5 397B |

### Reasoning

- Winner: Not comparable
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Qwen3.5 397B public-lane score: 61 (Unranked · 2 rankable rows)

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Qwen3.5 397B | Winner |
|-----------|-----------|-----------|--------|
| LongBench v2 | Coming soon | 63.2% | Coming soon |
| AI-Needle | Coming soon | 68.7% | Coming soon |

### Multimodal & Grounded

- Winner: Not comparable
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Qwen3.5 397B public-lane score: 63.9 (#27/49)

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Qwen3.5 397B | Winner |
|-----------|-----------|-----------|--------|
| MMMU-Pro | Coming soon | 79% | Coming soon |
| MathVision | Coming soon | 88.6% | Coming soon |
| CharXiv | Coming soon | 80.8% | Coming soon |
| VideoMMMU | Coming soon | 84.7% | Coming soon |
| ScreenSpot Pro | Coming soon | 65.6% | Coming soon |
| V* | Coming soon | 95.8% | Coming soon |

### Knowledge

- Winner: Not comparable
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Qwen3.5 397B public-lane score: 49.6 (Estimated · #68/174)

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Qwen3.5 397B | Winner |
|-----------|-----------|-----------|--------|
| MMLU-Redux | 87.8% | 94.9% | Qwen3.5 397B |
| GPQA-D | 64.6% | Coming soon | Coming soon |
| GPQA | Coming soon | 88.4% | Coming soon |
| SuperGPQA | Coming soon | 70.4% | Coming soon |
| MMLU-Pro | Coming soon | 87.8% | Coming soon |
| C-Eval | Coming soon | 93% | Coming soon |
| HLE | Coming soon | 28.7% | Coming soon |

### Multilingual

- Winner: Not comparable
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Qwen3.5 397B public-lane score: 93.8 (#5/16)

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Qwen3.5 397B | Winner |
|-----------|-----------|-----------|--------|
| MMLU-ProX | Coming soon | 84.7% | Coming soon |
| NOVA-63 | Coming soon | 59.1% | Coming soon |

### Instruction Following

- Winner: Not comparable
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Qwen3.5 397B public-lane score: 0 (#125/125)

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Qwen3.5 397B | Winner |
|-----------|-----------|-----------|--------|
| IFEval | 90.6% | 92.6% | Qwen3.5 397B |

### Mathematics

- Winner: Not comparable
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Qwen3.5 397B public-lane score: 73.5 (Unranked · 5 rankable rows)

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Qwen3.5 397B | Winner |
|-----------|-----------|-----------|--------|
| AIME26 | Coming soon | 93.3% | Coming soon |
| HMMT Feb 2025 | Coming soon | 94.8% | Coming soon |
| HMMT Nov 2025 | Coming soon | 92.7% | Coming soon |
| HMMT Feb 2026 | Coming soon | 87.9% | Coming soon |
| MMAnswerBench | Coming soon | 80.9% | Coming soon |

## FAQ

### Which is better overall, Mellum2.1-12B-A2.5B-Thinking or Qwen3.5 397B?

Qwen3.5 397B has the higher overall point estimate. Conditional score ranges do not establish rank confidence.

### How many benchmarks does Mellum2.1-12B-A2.5B-Thinking cover on BenchLM?

Mellum2.1-12B-A2.5B-Thinking currently has 7 sourced benchmark scores on BenchLM.

### How many benchmarks does Qwen3.5 397B cover on BenchLM?

Qwen3.5 397B currently has 38 sourced benchmark scores on BenchLM.

## Related Comparisons

- [Mellum2.1-12B-A2.5B-Thinking vs Qwen3.5 397B (Reasoning)](/compare/mellum2-1-12b-a2-5b-thinking-vs-qwen3-5-397b-reasoning)
- [Qwen3.5 397B vs Qwen3.5 397B (Reasoning)](/compare/qwen3-5-397b-vs-qwen3-5-397b-reasoning)
- [Mellum2.1-12B-A2.5B-Thinking vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-mellum2-1-12b-a2-5b-thinking)
- [Qwen3.5 397B vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-qwen3-5-397b)

## Explore More

- [Mellum2.1-12B-A2.5B-Thinking profile](/models/mellum2-1-12b-a2-5b-thinking)
- [Qwen3.5 397B profile](/models/qwen3-5-397b)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)