# Claude Opus 4.6 vs Mellum2-12B-A2.5B-Instruct

> Side-by-side benchmark comparison for Claude Opus 4.6 and Mellum2-12B-A2.5B-Instruct across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/claude-opus-4-6-vs-mellum2-12b-a2-5b-instruct
- Last updated: September 4, 2026

- Shared sourced benchmarks: 2
- HTML indexing: indexable
- Ranking lane: BenchAlign v5

## Quick Verdict

Evidence is too thin for a benchmark verdict: Claude Opus 4.6 and Mellum2-12B-A2.5B-Instruct share only 2 sourced benchmark rows.

## Summary

- Only 2 shared sourced benchmark rows are available. That is not enough for a broad capability verdict, so this mirror does not name an overall winner.
- Claude Opus 4.6 has the larger published context window at 1M.

## Model Snapshot

| Property | Claude Opus 4.6 | Mellum2-12B-A2.5B-Instruct |
|----------|----------|----------|
| Creator | Anthropic | JetBrains |
| Type | Proprietary | Open Weight |
| Reasoning | Non-Reasoning | Non-Reasoning |
| Context | 1M | 128K |
| Independent public score (not head-to-head) | 69.84 | null |
| Benchmarks Covered | 33 | 6 |
| Pricing (input/output) | $5.00 / $25.00 | N/A |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Claude Opus 4.6 public-lane score: 54.6 (Supported · #39/151)
- Mellum2-12B-A2.5B-Instruct public-lane score: 47.8 (Estimated · #82/151)

| Benchmark | Claude Opus 4.6 | Mellum2-12B-A2.5B-Instruct | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 2.0 | 65.4% | Coming soon | Coming soon |
| BrowseComp | 83.7% | Coming soon | Coming soon |
| OSWorld-Verified | 72.7% | Coming soon | Coming soon |
| Claw-Eval | 70.4% | Coming soon | Coming soon |
| DeepSearchQA | 73.7% | Coming soon | Coming soon |
| CyberGym | 66.6% | Coming soon | Coming soon |
| Gert Labs | 61.85% | Coming soon | Coming soon |
| ResearchClawBench | 19.9% | Coming soon | Coming soon |
| JobBench | 36.7% | Coming soon | Coming soon |
| BFCL v4 | Coming soon | 44.2% | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- Claude Opus 4.6 public-lane score: 56.5 (Supported · #40/183)
- Mellum2-12B-A2.5B-Instruct public-lane score: Coming soon

| Benchmark | Claude Opus 4.6 | Mellum2-12B-A2.5B-Instruct | Winner |
|-----------|-----------|-----------|--------|
| SWE-bench Verified | 80.8% | Coming soon | Coming soon |
| SWE-bench Verified* | 75.6% | Coming soon | Coming soon |
| LiveCodeBench Pro | 70.7% | Coming soon | Coming soon |
| SWE-bench Pro | 53.4% | Coming soon | Coming soon |
| SWE-Rebench | 65.3% | Coming soon | Coming soon |
| React Native Evals | 84.1% | Coming soon | Coming soon |
| Vibe Code Bench | 57.57% | Coming soon | Coming soon |
| FrontierCode 1.1 Main | 26.9% | Coming soon | Coming soon |
| LiveCodeBench v6 | Coming soon | 37.2% | Coming soon |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- Claude Opus 4.6 public-lane score: 59.5 (#28/48)
- Mellum2-12B-A2.5B-Instruct public-lane score: Coming soon

| Benchmark | Claude Opus 4.6 | Mellum2-12B-A2.5B-Instruct | Winner |
|-----------|-----------|-----------|--------|
| MMMU-Pro | 77.3% | Coming soon | Coming soon |
| ERQA | 51.6% | Coming soon | Coming soon |
| ScreenSpot Pro | 83.1% | Coming soon | Coming soon |
| MedXpertQA (MM) | 64.8% | Coming soon | Coming soon |

### Reasoning

- Winner: Insufficient shared evidence
- Claude Opus 4.6 public-lane score: 65.8 (Unranked · 2 rankable rows)
- Mellum2-12B-A2.5B-Instruct public-lane score: Coming soon

### Knowledge

- Winner: Insufficient shared evidence
- Claude Opus 4.6 public-lane score: 61.8 (Estimated · #33/181)
- Mellum2-12B-A2.5B-Instruct public-lane score: 48.1 (Estimated · #103/181)

| Benchmark | Claude Opus 4.6 | Mellum2-12B-A2.5B-Instruct | Winner |
|-----------|-----------|-----------|--------|
| GPQA | 91.3% | 40.9% | Claude Opus 4.6 |
| GPQA-D | 89.2% | 40.9% | Claude Opus 4.6 |
| SuperGPQA | 95% | Coming soon | Coming soon |
| MMLU-Pro | 82% | Coming soon | Coming soon |
| MMLU-Pro (Arcee) | 89.1% | Coming soon | Coming soon |
| HLE | 53% | Coming soon | Coming soon |
| HLE w/o tools | 40% | Coming soon | Coming soon |
| HealthBench Hard | 14.8% | Coming soon | Coming soon |
| MedXpertQA (Text) | 52.1% | Coming soon | Coming soon |
| MMLU-Redux | Coming soon | 78.1% | Coming soon |

### Instruction Following

- Winner: Insufficient shared evidence
- Claude Opus 4.6 public-lane score: 52.3 (#76/120)
- Mellum2-12B-A2.5B-Instruct public-lane score: Coming soon

| Benchmark | Claude Opus 4.6 | Mellum2-12B-A2.5B-Instruct | Winner |
|-----------|-----------|-----------|--------|
| IFEval | Coming soon | 75.8% | Coming soon |

### Mathematics

- Winner: Insufficient shared evidence
- Claude Opus 4.6 public-lane score: 58.6 (Unranked · 3 rankable rows)
- Mellum2-12B-A2.5B-Instruct public-lane score: Coming soon

| Benchmark | Claude Opus 4.6 | Mellum2-12B-A2.5B-Instruct | Winner |
|-----------|-----------|-----------|--------|
| AIME25 (Arcee) | 99.8% | Coming soon | Coming soon |
| FrontierMath v2 (Tiers 1-3) | 40.700% | Coming soon | Coming soon |
| FrontierMath v2 (Tier 4) | 22.900% | Coming soon | Coming soon |

## FAQ

### Is there enough evidence to pick between Claude Opus 4.6 and Mellum2-12B-A2.5B-Instruct?

Not yet. The models share only 2 sourced benchmark rows, 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

- [Claude Opus 4.6 vs Claude Opus 4.6 (Adaptive)](/compare/claude-opus-4-6-vs-claude-opus-4-6-thinking)
- [Mellum2-12B-A2.5B-Instruct vs Claude Opus 4.6 (Adaptive)](/compare/claude-opus-4-6-thinking-vs-mellum2-12b-a2-5b-instruct)
- [Claude Opus 4.6 vs Mellum2-12B-A2.5B-Thinking](/compare/claude-opus-4-6-vs-mellum2-12b-a2-5b-thinking)
- [Mellum2-12B-A2.5B-Instruct vs Mellum2-12B-A2.5B-Thinking](/compare/mellum2-12b-a2-5b-instruct-vs-mellum2-12b-a2-5b-thinking)

## Explore More

- [Claude Opus 4.6 profile](/models/claude-opus-4-6)
- [Mellum2-12B-A2.5B-Instruct profile](/models/mellum2-12b-a2-5b-instruct)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)