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Mellum2-12B-A2.5B-Thinking vs o1-pro

Head-to-head comparison across 1benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.

Mellum2-12B-A2.5B-Thinking

59

VS

o1-pro

28

0 categoriesvs1 categories

Pick Mellum2-12B-A2.5B-Thinking if you want the stronger benchmark profile. o1-pro only becomes the better choice if knowledge is the priority or you need the larger 200K context window.

Category Radar

Head-to-Head by Category

Category Breakdown

Knowledge

o1-pro
57.6vs79

+21.4 difference

Operational Comparison

Mellum2-12B-A2.5B-Thinking

o1-pro

Price (per 1M tokens)

N/A

$150 / $600

Speed

N/A

N/A

Latency (TTFT)

N/A

N/A

Context Window

128K

200K

Quick Verdict

Pick Mellum2-12B-A2.5B-Thinking if you want the stronger benchmark profile. o1-pro only becomes the better choice if knowledge is the priority or you need the larger 200K context window.

Mellum2-12B-A2.5B-Thinking is clearly ahead on the provisional aggregate, 59 to 28. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

o1-pro gives you the larger context window at 200K, compared with 128K for Mellum2-12B-A2.5B-Thinking.

Benchmark Deep Dive

Frequently Asked Questions (2)

Which is better, Mellum2-12B-A2.5B-Thinking or o1-pro?

Mellum2-12B-A2.5B-Thinking is ahead on BenchLM's provisional leaderboard, 59 to 28. The biggest single separator in this matchup is GPQA, where the scores are 57.6% and 79%.

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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Last updated: June 8, 2026

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