Model comparison
Mellum2-12B-A2.5B-Thinking vs o1-pro
Head-to-head evidence from 1 shared benchmark result across 1 category. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Mellum2-12B-A2.5B-Thinking unranked (Not scored); o1-pro #141 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Mellum2-12B-A2.5B-Thinking and o1-pro share 1 comparable benchmark result. 1 of 8 categories are comparable. 4 results are unique to Mellum2-12B-A2.5B-Thinking; 1 to o1-pro.
Updated July 23, 2026- Shared results
- 1
- Mellum2-12B-A2.5B-Thinking only
- 4
- o1-pro only
- 1
- Comparable categories
- 1 / 8
Treat this as a split decision. Mellum2-12B-A2.5B-Thinking makes more sense if its workflow fits your team better; o1-pro is the better fit if knowledge is the priority or you need the larger 200K context window.
Confidence note. This is a partial-evidence comparison with 1 shared benchmark result across 1 evidence category; 1 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
Mellum2-12B-A2.5B-Thinking and o1-pro finish on the same BenchAlign overall score, so this is less about a single winner and more about where the edge shows up. The BenchAlign headline says tie; the benchmark table is where the real choice happens.
o1-pro gives you the larger context window at 200K, compared with 128K for Mellum2-12B-A2.5B-Thinking.
Category breakdown
Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.
| Category | Mellum2-12B-A2.5B-Thinking | Δ | o1-pro |
|---|---|---|---|
| Knowledge | Mellum2-12B-A2.5B-Thinking57.6 | Margin→ 21.4 | o1-pro79.0 |
| Inst. Following | Mellum2-12B-A2.5B-Thinking76.5 | MarginNo overlap | o1-proNot measured |
Decisive benchmark drivers
The largest measured benchmark gaps in this matchup, with exact reported values.
More
- Source ↗
GPQA
KnowledgeA 57.6%B 79%Winner: o1-proΔ 21.4GPQA: Mellum2-12B-A2.5B-Thinking scored 57.6%; o1-pro scored 79%. o1-pro wins this benchmark.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Mellum2-12B-A2.5B-Thinking | o1-pro | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Mellum2-12B-A2.5B-ThinkingNot available | o1-pro$150 input / $600 output | A complete price comparison is not available. |
| Generation speedtokens per second | Mellum2-12B-A2.5B-ThinkingNot available | o1-proNot available | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Mellum2-12B-A2.5B-ThinkingNot available | o1-proNot available | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Mellum2-12B-A2.5B-Thinking128K | o1-pro200K | o1-pro lists the larger context window. |
Benchmark Deep Dive
Frequently Asked Questions (2)
Which is better, Mellum2-12B-A2.5B-Thinking or o1-pro?
Mellum2-12B-A2.5B-Thinking and o1-pro are tied on the BenchAlign overall score, so the right pick depends on which category matters most for your use case.
Which is better for knowledge tasks, Mellum2-12B-A2.5B-Thinking or o1-pro?
o1-pro has the edge for knowledge tasks in this comparison, averaging 79 versus 57.6. Inside this category, GPQA is the benchmark that creates the most daylight between them.
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