# GPT-6 Luna vs Mellum2-12B-A2.5B-Instruct

> Side-by-side benchmark comparison for GPT-6 Luna and Mellum2-12B-A2.5B-Instruct across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gpt-6-luna-vs-mellum2-12b-a2-5b-instruct
- Last updated: September 22, 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 GPT-6 Luna and Mellum2-12B-A2.5B-Instruct.

## Summary

- GPT-6 Luna and Mellum2-12B-A2.5B-Instruct 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 | GPT-6 Luna | Mellum2-12B-A2.5B-Instruct |
|----------|----------|----------|
| Creator | OpenAI | JetBrains |
| Type | Proprietary | Open Weight |
| Reasoning | Reasoning | Non-Reasoning |
| Context | 1.05M | 128K |
| Independent public score (not head-to-head) | 62.33 | null |
| Benchmarks Covered | 7 | 6 |
| Pricing (input/output) | $0.10 / $0.50 | N/A |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- GPT-6 Luna public-lane score: 56.7 (Estimated · #35/157)
- Mellum2-12B-A2.5B-Instruct public-lane score: 46.2 (Estimated · #87/157)

| Benchmark | GPT-6 Luna | Mellum2-12B-A2.5B-Instruct | Winner |
|-----------|-----------|-----------|--------|
| ExploitGym | 11.6% | Coming soon | Coming soon |
| BFCL v4 | Coming soon | 44.2% | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- GPT-6 Luna public-lane score: 66.6 (Estimated · #11/159)
- Mellum2-12B-A2.5B-Instruct public-lane score: Coming soon

| Benchmark | GPT-6 Luna | Mellum2-12B-A2.5B-Instruct | Winner |
|-----------|-----------|-----------|--------|
| DeepSWE | 66.6% | Coming soon | Coming soon |
| LiveCodeBench v6 | Coming soon | 37.2% | Coming soon |

### Reasoning

- Winner: Insufficient shared evidence
- GPT-6 Luna public-lane score: 78.3 (Unranked · 2 rankable rows)
- Mellum2-12B-A2.5B-Instruct public-lane score: Coming soon

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- GPT-6 Luna public-lane score: 71.3 (Unranked · 1 rankable row)
- Mellum2-12B-A2.5B-Instruct public-lane score: Coming soon

### Knowledge

- Winner: Insufficient shared evidence
- GPT-6 Luna public-lane score: 63.6 (Estimated · #29/189)
- Mellum2-12B-A2.5B-Instruct public-lane score: 46.4 (Estimated · #113/189)

| Benchmark | GPT-6 Luna | Mellum2-12B-A2.5B-Instruct | Winner |
|-----------|-----------|-----------|--------|
| HealthBench (raw) | 50.0% | Coming soon | Coming soon |
| HealthBench (length-adjusted) | 54.5% | Coming soon | Coming soon |
| HealthBench Professional | 60.8% | Coming soon | Coming soon |
| HealthBench Professional (raw) | 61.2% | Coming soon | Coming soon |
| HealthBench Hard | 31.4% | Coming soon | Coming soon |
| MMLU-Redux | Coming soon | 78.1% | Coming soon |
| GPQA | Coming soon | 40.9% | Coming soon |
| GPQA-D | Coming soon | 40.9% | Coming soon |

### Instruction Following

- Winner: Insufficient shared evidence
- GPT-6 Luna public-lane score: Coming soon
- Mellum2-12B-A2.5B-Instruct public-lane score: Coming soon

| Benchmark | GPT-6 Luna | Mellum2-12B-A2.5B-Instruct | Winner |
|-----------|-----------|-----------|--------|
| IFEval | Coming soon | 75.8% | Coming soon |

## FAQ

### Can I compare GPT-6 Luna and Mellum2-12B-A2.5B-Instruct 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

- [GPT-6 Luna vs GPT-6 Astra](/compare/gpt-6-astra-vs-gpt-6-luna)
- [Mellum2-12B-A2.5B-Instruct vs GPT-6 Astra](/compare/gpt-6-astra-vs-mellum2-12b-a2-5b-instruct)
- [GPT-6 Luna vs GPT-6 Sol](/compare/gpt-6-luna-vs-gpt-6-sol)
- [Mellum2-12B-A2.5B-Instruct vs GPT-6 Sol](/compare/gpt-6-sol-vs-mellum2-12b-a2-5b-instruct)

## Explore More

- [GPT-6 Luna profile](/models/gpt-6-luna)
- [Mellum2-12B-A2.5B-Instruct profile](/models/mellum2-12b-a2-5b-instruct)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)