# Mellum2.1-12B-A2.5B-Thinking vs Ornith-1.5-35B-A3B

> Side-by-side benchmark comparison for Mellum2.1-12B-A2.5B-Thinking and Ornith-1.5-35B-A3B across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/mellum2-1-12b-a2-5b-thinking-vs-ornith-1-5-35b-a3b
- Last updated: October 8, 2026

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

## Quick Verdict

Mellum2.1-12B-A2.5B-Thinking leads by point estimate. Conditional score ranges do not establish rank confidence. Choose using the category evidence and your own workload tests.

## Summary

- Mellum2.1-12B-A2.5B-Thinking has the higher overall point estimate 37 to 32.94. Conditional score ranges do not establish rank confidence.
- The biggest single benchmark swing is Terminal-Bench 2.1 in Agentic, with scores of 17.4% and 67.8%.
- Ornith-1.5-35B-A3B also has the larger context window at 262K.

## Model Snapshot

| Property | Mellum2.1-12B-A2.5B-Thinking | Ornith-1.5-35B-A3B |
|----------|----------|----------|
| Creator | JetBrains | Ornith AI |
| Type | Open Weight | Open Weight |
| Reasoning | Reasoning | Reasoning |
| Context | 128K | 262K |
| Overall Score | null | 32.94 |
| Benchmarks Covered | 7 | 18 |
| Pricing (input/output) | $0.00 / $0.00 | $0.00 / $0.00 |

## Category Breakdown

### Agentic

- Winner: Not comparable
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Ornith-1.5-35B-A3B public-lane score: 24.9 (Estimated · #95/122)

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Ornith-1.5-35B-A3B | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 2.1 | 17.4% | 67.8% | Ornith-1.5-35B-A3B |
| HLE w/ tools | Coming soon | 33.4% | Coming soon |
| MCP Atlas | Coming soon | 70.2% | Coming soon |
| Toolathlon-Verified | Coming soon | 48.7% | Coming soon |
| WideResearch | Coming soon | 67.8% | Coming soon |
| BrowseComp | Coming soon | 67.6% | Coming soon |
| Claw-Eval | Coming soon | 72.5% | Coming soon |

### Coding

- Winner: Not comparable
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Ornith-1.5-35B-A3B public-lane score: 23.5 (Estimated · #109/146)

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Ornith-1.5-35B-A3B | Winner |
|-----------|-----------|-----------|--------|
| LiveCodeBench v6 | 82.0% | Coming soon | Coming soon |
| SWE-bench Verified | 47% | 79% | Ornith-1.5-35B-A3B |
| SWE-bench Pro | 28% | 59.6% | Ornith-1.5-35B-A3B |
| Terminal-Bench 2.1 | Coming soon | 67.8% | Coming soon |
| SWE Multilingual | Coming soon | 71.4% | Coming soon |
| DeepSWE | Coming soon | 22.0% | Coming soon |
| frontierBench | Coming soon | 5.1% | Coming soon |
| NL2Repo | Coming soon | 46.2% | Coming soon |

### Knowledge

- Winner: Not comparable
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Ornith-1.5-35B-A3B public-lane score: 35.4 (Estimated · #120/174)

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Ornith-1.5-35B-A3B | Winner |
|-----------|-----------|-----------|--------|
| MMLU-Redux | 87.8% | Coming soon | Coming soon |
| GPQA-D | 64.6% | 89.2% | Ornith-1.5-35B-A3B |
| GPQA | Coming soon | 89.2% | Coming soon |
| HLE | Coming soon | 25.6% | Coming soon |
| HLE w/o tools | Coming soon | 25.6% | Coming soon |

### Instruction Following

- Winner: Not comparable
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Ornith-1.5-35B-A3B public-lane score: Coming soon

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Ornith-1.5-35B-A3B | Winner |
|-----------|-----------|-----------|--------|
| IFEval | 90.6% | Coming soon | Coming soon |

## FAQ

### Which is better overall, Mellum2.1-12B-A2.5B-Thinking or Ornith-1.5-35B-A3B?

Mellum2.1-12B-A2.5B-Thinking 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 Ornith-1.5-35B-A3B cover on BenchLM?

Ornith-1.5-35B-A3B currently has 18 sourced benchmark scores on BenchLM.

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- [Ornith-1.5-35B-A3B vs Ornith-1.5-9B](/compare/ornith-1-5-35b-a3b-vs-ornith-1-5-9b)

## Explore More

- [Mellum2.1-12B-A2.5B-Thinking profile](/models/mellum2-1-12b-a2-5b-thinking)
- [Ornith-1.5-35B-A3B profile](/models/ornith-1-5-35b-a3b)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)