# Mellum2-12B-A2.5B-Thinking vs Beam

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

- Canonical page: https://benchlm.ai/compare/mellum2-12b-a2-5b-thinking-vs-reflection-beam
- Last updated: October 5, 2026

- Shared sourced benchmarks: 1
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.8

## Quick Verdict

Evidence is too thin for a benchmark verdict: Mellum2-12B-A2.5B-Thinking and Beam share only 1 sourced benchmark row.

## Summary

- Only 1 shared sourced benchmark row is available. That is not enough for a broad capability verdict, so this mirror does not name an overall winner.
- Mellum2-12B-A2.5B-Thinking has the larger published context window at 128K.

## Model Snapshot

| Property | Mellum2-12B-A2.5B-Thinking | Beam |
|----------|----------|----------|
| Creator | JetBrains | Reflection AI |
| Type | Open Weight | Pending |
| Reasoning | Reasoning | Reasoning |
| Context | 128K | null |
| Independent public score (not head-to-head) | null | null |
| Benchmarks Covered | 6 | 16 |
| Pricing (input/output) | N/A | Pricing unavailable / Pricing unavailable |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Thinking public-lane score: Coming soon
- Beam public-lane score: Coming soon

| Benchmark | Mellum2-12B-A2.5B-Thinking | Beam | Winner |
|-----------|-----------|-----------|--------|
| BFCL v4 | 45.6% | Coming soon | Coming soon |
| Terminal-Bench 2.1 | Coming soon | 80.1% | Coming soon |
| MCP Atlas | Coming soon | 78.7% | Coming soon |
| BrowseComp | Coming soon | 77.4% | Coming soon |
| DeepSearchQA | Coming soon | 80.1% | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Thinking public-lane score: Coming soon
- Beam public-lane score: Coming soon

| Benchmark | Mellum2-12B-A2.5B-Thinking | Beam | Winner |
|-----------|-----------|-----------|--------|
| LiveCodeBench v6 | 69.9% | Coming soon | Coming soon |
| DeepSWE | Coming soon | 44.4% | Coming soon |
| SWE-bench Pro | Coming soon | 65.5% | Coming soon |
| Terminal-Bench 2.1 | Coming soon | 80.1% | Coming soon |
| SWE-Atlas Codebase QnA | Coming soon | 34.6% | Coming soon |
| SWE Multilingual | Coming soon | 78% | Coming soon |
| SWE-bench Verified | Coming soon | 80.9% | Coming soon |
| SciCode | Coming soon | 49.7% | Coming soon |

### Reasoning

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Thinking public-lane score: Coming soon
- Beam public-lane score: Coming soon

| Benchmark | Mellum2-12B-A2.5B-Thinking | Beam | Winner |
|-----------|-----------|-----------|--------|
| LongBench v2 | Coming soon | 65.5% | Coming soon |

### Knowledge

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Thinking public-lane score: Coming soon
- Beam public-lane score: Coming soon

| Benchmark | Mellum2-12B-A2.5B-Thinking | Beam | Winner |
|-----------|-----------|-----------|--------|
| MMLU-Redux | 86.2% | Coming soon | Coming soon |
| GPQA | 57.6% | Coming soon | Coming soon |
| GPQA-D | 57.6% | 90.5% | Beam |
| HLE w/o tools | Coming soon | 36.2% | Coming soon |

### Instruction Following

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Thinking public-lane score: Coming soon
- Beam public-lane score: Coming soon

| Benchmark | Mellum2-12B-A2.5B-Thinking | Beam | Winner |
|-----------|-----------|-----------|--------|
| IFEval | 76.5% | Coming soon | Coming soon |
| IFBench | Coming soon | 79.7% | Coming soon |

### Mathematics

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Thinking public-lane score: Coming soon
- Beam public-lane score: Coming soon

| Benchmark | Mellum2-12B-A2.5B-Thinking | Beam | Winner |
|-----------|-----------|-----------|--------|
| AIME26 | Coming soon | 97.8% | Coming soon |

## FAQ

### Is there enough evidence to pick between Mellum2-12B-A2.5B-Thinking and Beam?

Not yet. The models share only 1 sourced benchmark row, 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

- [Mellum2-12B-A2.5B-Thinking vs Mellum2-12B-A2.5B-Instruct](/compare/mellum2-12b-a2-5b-instruct-vs-mellum2-12b-a2-5b-thinking)
- [Beam vs Mellum2-12B-A2.5B-Instruct](/compare/mellum2-12b-a2-5b-instruct-vs-reflection-beam)
- [Mellum2-12B-A2.5B-Thinking vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-mellum2-12b-a2-5b-thinking)
- [Beam vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-reflection-beam)

## Explore More

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