# Mellum2-12B-A2.5B-Instruct vs o3-mini

> Side-by-side benchmark comparison for Mellum2-12B-A2.5B-Instruct and o3-mini across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/mellum2-12b-a2-5b-instruct-vs-o3-mini
- 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: Mellum2-12B-A2.5B-Instruct and o3-mini 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.
- o3-mini has the larger published context window at 200K.

## Model Snapshot

| Property | Mellum2-12B-A2.5B-Instruct | o3-mini |
|----------|----------|----------|
| Creator | JetBrains | OpenAI |
| Type | Open Weight | Proprietary |
| Reasoning | Non-Reasoning | Reasoning |
| Context | 128K | 200K |
| Independent public score (not head-to-head) | null | 48.06 |
| Benchmarks Covered | 6 | 5 |
| Pricing (input/output) | N/A | $1.10 / $4.40 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Instruct public-lane score: 47.8 (Estimated · #82/151)
- o3-mini public-lane score: Coming soon

| Benchmark | Mellum2-12B-A2.5B-Instruct | o3-mini | Winner |
|-----------|-----------|-----------|--------|
| BFCL v4 | 44.2% | Coming soon | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Instruct public-lane score: Coming soon
- o3-mini public-lane score: 40.6 (Supported · #140/183)

| Benchmark | Mellum2-12B-A2.5B-Instruct | o3-mini | Winner |
|-----------|-----------|-----------|--------|
| LiveCodeBench v6 | 37.2% | Coming soon | Coming soon |
| SWE-bench Verified | Coming soon | 49.3% | Coming soon |

### Knowledge

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Instruct public-lane score: 48.1 (Estimated · #103/181)
- o3-mini public-lane score: 42.3 (Supported · #127/181)

| Benchmark | Mellum2-12B-A2.5B-Instruct | o3-mini | Winner |
|-----------|-----------|-----------|--------|
| MMLU-Redux | 78.1% | Coming soon | Coming soon |
| GPQA | 40.9% | 77.2% | o3-mini |
| GPQA-D | 40.9% | Coming soon | Coming soon |
| MMLU | Coming soon | 86.9% | Coming soon |

### Instruction Following

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Instruct public-lane score: Coming soon
- o3-mini public-lane score: Coming soon

| Benchmark | Mellum2-12B-A2.5B-Instruct | o3-mini | Winner |
|-----------|-----------|-----------|--------|
| IFEval | 75.8% | 93.9% | o3-mini |

### Mathematics

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Instruct public-lane score: Coming soon
- o3-mini public-lane score: Coming soon

| Benchmark | Mellum2-12B-A2.5B-Instruct | o3-mini | Winner |
|-----------|-----------|-----------|--------|
| AIME 2024 | Coming soon | 87.3% | Coming soon |

## FAQ

### Is there enough evidence to pick between Mellum2-12B-A2.5B-Instruct and o3-mini?

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

- [Mellum2-12B-A2.5B-Instruct vs Mellum2-12B-A2.5B-Thinking](/compare/mellum2-12b-a2-5b-instruct-vs-mellum2-12b-a2-5b-thinking)
- [o3-mini vs Mellum2-12B-A2.5B-Thinking](/compare/mellum2-12b-a2-5b-thinking-vs-o3-mini)
- [Mellum2-12B-A2.5B-Instruct vs o3-pro](/compare/mellum2-12b-a2-5b-instruct-vs-o3-pro)
- [o3-mini vs o3-pro](/compare/o3-mini-vs-o3-pro)

## Explore More

- [Mellum2-12B-A2.5B-Instruct profile](/models/mellum2-12b-a2-5b-instruct)
- [o3-mini profile](/models/o3-mini)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)