# Claude 4.1 Opus Thinking vs Mellum2-12B-A2.5B-Thinking

> Side-by-side benchmark comparison for Claude 4.1 Opus Thinking and Mellum2-12B-A2.5B-Thinking across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/claude-4-1-opus-thinking-vs-mellum2-12b-a2-5b-thinking
- Last updated: September 4, 2026

- Shared sourced benchmarks: 0
- HTML indexing: indexable
- Ranking lane: BenchAlign v5

## Quick Verdict

No benchmark verdict yet: there is no shared sourced benchmark row for Claude 4.1 Opus Thinking and Mellum2-12B-A2.5B-Thinking.

## Summary

- Claude 4.1 Opus Thinking and Mellum2-12B-A2.5B-Thinking do not currently share a sourced benchmark row. The mirror therefore compares metadata, pricing, context windows, and each model's separately reported coverage without naming a benchmark winner.

## Model Snapshot

| Property | Claude 4.1 Opus Thinking | Mellum2-12B-A2.5B-Thinking |
|----------|----------|----------|
| Creator | Anthropic | JetBrains |
| Type | Proprietary | Open Weight |
| Reasoning | Reasoning | Reasoning |
| Context | 200K | 128K |
| Independent public score (not head-to-head) | 34.62 | null |
| Benchmarks Covered | 0 | 6 |
| Pricing (input/output) | Pricing unavailable / Pricing unavailable | N/A |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Claude 4.1 Opus Thinking public-lane score: Coming soon
- Mellum2-12B-A2.5B-Thinking public-lane score: 48.3 (Estimated · #76/151)

| Benchmark | Claude 4.1 Opus Thinking | Mellum2-12B-A2.5B-Thinking | Winner |
|-----------|-----------|-----------|--------|
| BFCL v4 | Coming soon | 45.6% | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- Claude 4.1 Opus Thinking public-lane score: 37.3 (Estimated · #151/183)
- Mellum2-12B-A2.5B-Thinking public-lane score: Coming soon

| Benchmark | Claude 4.1 Opus Thinking | Mellum2-12B-A2.5B-Thinking | Winner |
|-----------|-----------|-----------|--------|
| LiveCodeBench v6 | Coming soon | 69.9% | Coming soon |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- Claude 4.1 Opus Thinking public-lane score: 60 (Unranked · 1 rankable row)
- Mellum2-12B-A2.5B-Thinking public-lane score: Coming soon

### Reasoning

- Winner: Insufficient shared evidence
- Claude 4.1 Opus Thinking public-lane score: 73.7 (Unranked · 2 rankable rows)
- Mellum2-12B-A2.5B-Thinking public-lane score: Coming soon

### Knowledge

- Winner: Insufficient shared evidence
- Claude 4.1 Opus Thinking public-lane score: 38.5 (Estimated · #146/181)
- Mellum2-12B-A2.5B-Thinking public-lane score: 48.8 (Estimated · #96/181)

| Benchmark | Claude 4.1 Opus Thinking | Mellum2-12B-A2.5B-Thinking | Winner |
|-----------|-----------|-----------|--------|
| MMLU-Redux | Coming soon | 86.2% | Coming soon |
| GPQA | Coming soon | 57.6% | Coming soon |
| GPQA-D | Coming soon | 57.6% | Coming soon |

### Instruction Following

- Winner: Insufficient shared evidence
- Claude 4.1 Opus Thinking public-lane score: 66.3 (#65/120)
- Mellum2-12B-A2.5B-Thinking public-lane score: Coming soon

| Benchmark | Claude 4.1 Opus Thinking | Mellum2-12B-A2.5B-Thinking | Winner |
|-----------|-----------|-----------|--------|
| IFEval | Coming soon | 76.5% | Coming soon |

## FAQ

### Can I compare Claude 4.1 Opus Thinking and Mellum2-12B-A2.5B-Thinking on BenchLM yet?

Not fully yet. BenchLM is tracking both models, but sourced benchmark coverage is still incomplete for a fair score-level comparison.

### Why does this page show "coming soon" values?

BenchLM only calls winners when public benchmark coverage is available on both sides of the comparison.

## Related Comparisons

- [Claude 4.1 Opus Thinking vs Claude 4.1 Opus](/compare/claude-4-1-opus-vs-claude-4-1-opus-thinking)
- [Mellum2-12B-A2.5B-Thinking vs Claude 4.1 Opus](/compare/claude-4-1-opus-vs-mellum2-12b-a2-5b-thinking)
- [Claude 4.1 Opus Thinking vs Mellum2-12B-A2.5B-Instruct](/compare/claude-4-1-opus-thinking-vs-mellum2-12b-a2-5b-instruct)
- [Mellum2-12B-A2.5B-Thinking vs Mellum2-12B-A2.5B-Instruct](/compare/mellum2-12b-a2-5b-instruct-vs-mellum2-12b-a2-5b-thinking)

## Explore More

- [Claude 4.1 Opus Thinking profile](/models/claude-4-1-opus-thinking)
- [Mellum2-12B-A2.5B-Thinking profile](/models/mellum2-12b-a2-5b-thinking)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)