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

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

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

- Shared sourced benchmarks: 4
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.8

## Quick Verdict

Pick Mellum2-12B-A2.5B-Thinking if you want the stronger benchmark profile. Mellum2.1-12B-A2.5B-Thinking only makes more sense when its price, context window, or workload-specific category wins matter more than the overall score.

## Summary

- Mellum2-12B-A2.5B-Thinking leads overall 54 to 37.
- The biggest single benchmark swing is IFEval in Instruction Following, with scores of 90.6% and 76.5%.

## Model Snapshot

| Property | Mellum2.1-12B-A2.5B-Thinking | Mellum2-12B-A2.5B-Thinking |
|----------|----------|----------|
| Creator | JetBrains | JetBrains |
| Type | Open Weight | Open Weight |
| Reasoning | Reasoning | Reasoning |
| Context | 128K | 128K |
| Overall Score | null | null |
| Benchmarks Covered | 7 | 6 |
| Pricing (input/output) | $0.00 / $0.00 | N/A |

## Category Breakdown

### Agentic

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

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Mellum2-12B-A2.5B-Thinking | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 2.1 | 17.4% | Coming soon | Coming soon |
| BFCL v4 | Coming soon | 45.6% | Coming soon |

### Coding

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

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Mellum2-12B-A2.5B-Thinking | Winner |
|-----------|-----------|-----------|--------|
| LiveCodeBench v6 | 82.0% | 69.9% | Mellum2.1-12B-A2.5B-Thinking |
| SWE-bench Verified | 47% | Coming soon | Coming soon |
| SWE-bench Pro | 28% | Coming soon | Coming soon |

### Knowledge

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

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Mellum2-12B-A2.5B-Thinking | Winner |
|-----------|-----------|-----------|--------|
| MMLU-Redux | 87.8% | 86.2% | Mellum2.1-12B-A2.5B-Thinking |
| GPQA-D | 64.6% | 57.6% | Mellum2.1-12B-A2.5B-Thinking |
| GPQA | Coming soon | 57.6% | Coming soon |

### Instruction Following

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

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Mellum2-12B-A2.5B-Thinking | Winner |
|-----------|-----------|-----------|--------|
| IFEval | 90.6% | 76.5% | Mellum2.1-12B-A2.5B-Thinking |

## FAQ

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

Mellum2-12B-A2.5B-Thinking is ahead overall on BenchLM right now.

### 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 Mellum2-12B-A2.5B-Thinking cover on BenchLM?

Mellum2-12B-A2.5B-Thinking currently has 6 sourced benchmark scores on BenchLM.

## Related Comparisons

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

## Explore More

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