Model comparison
Mellum2-12B-A2.5B-Thinking vs o1-preview
Head-to-head evidence from 0 shared benchmark results across 0 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Mellum2-12B-A2.5B-Thinking unranked (Not scored); o1-preview #123 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Mellum2-12B-A2.5B-Thinking and o1-preview share 0 comparable benchmark results. 0 of 8 categories are comparable. 5 results are unique to Mellum2-12B-A2.5B-Thinking; 2 to o1-preview.
Updated July 23, 2026- Shared results
- 0
- Mellum2-12B-A2.5B-Thinking only
- 5
- o1-preview only
- 2
- Comparable categories
- 0 / 8
Benchmark data for Mellum2-12B-A2.5B-Thinking and o1-preview is coming soon on BenchLM.
Confidence note. This is a partial-evidence comparison with 0 shared benchmark results across 0 evidence categories; 0 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
BenchLM has partial data for these models, but not enough overlapping benchmark coverage to produce a fair score-level comparison yet.
o1-preview has the larger context window at 200K, compared with 128K for Mellum2-12B-A2.5B-Thinking.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Mellum2-12B-A2.5B-Thinking | o1-preview | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Mellum2-12B-A2.5B-ThinkingNot available | o1-preview$15 input / $60 output | A complete price comparison is not available. |
| Generation speedtokens per second | Mellum2-12B-A2.5B-ThinkingNot available | o1-previewNot available | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Mellum2-12B-A2.5B-ThinkingNot available | o1-previewNot available | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Mellum2-12B-A2.5B-Thinking128K | o1-preview200K | o1-preview lists the larger context window. |
Benchmark Deep Dive
Agentic1 benchmarks
| Benchmark | Mellum2-12B-A2.5B-Thinking | o1-preview | Result |
|---|---|---|---|
| BFCL v4Source | 45.6% | — | Not comparable |
Coding1 benchmarks
| Benchmark | Mellum2-12B-A2.5B-Thinking | o1-preview | Result |
|---|---|---|---|
| AA Coding IndexSource | — | 34.0% | Not comparable |
Knowledge4 benchmarks
Inst. Following1 benchmarks
| Benchmark | Mellum2-12B-A2.5B-Thinking | o1-preview | Result |
|---|---|---|---|
| IFEvalSource | 76.5% | — | Not comparable |
Frequently Asked Questions (3)
Can I compare Mellum2-12B-A2.5B-Thinking and o1-preview on BenchLM yet?
Not fully yet. BenchLM is tracking both models, but the sourced benchmark breakdown for this comparison is still coming soon.
Why does this comparison show “coming soon”?
BenchLM only shows category winners and benchmark-level calls when we have sourced results that can be compared fairly. For these models, the public benchmark coverage is not complete enough yet.
What data is available for Mellum2-12B-A2.5B-Thinking and o1-preview today?
o1-preview: $15.00 input / $60.00 output per 1M tokens Both model pages still include creator, context window, reasoning mode, and other metadata while benchmark coverage fills in.
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