Head-to-head comparison across 1benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
GPT-5.4 mini
69
Mellum2-12B-A2.5B-Thinking
59
Pick GPT-5.4 mini if you want the stronger benchmark profile. Mellum2-12B-A2.5B-Thinking only becomes the better choice if knowledge is the priority.
Knowledge
+0.2 difference
GPT-5.4 mini
Mellum2-12B-A2.5B-Thinking
$0.75 / $4.5
N/A
201 t/s
N/A
3.85s
N/A
400K
128K
Pick GPT-5.4 mini if you want the stronger benchmark profile. Mellum2-12B-A2.5B-Thinking only becomes the better choice if knowledge is the priority.
GPT-5.4 mini is clearly ahead on the provisional aggregate, 69 to 59. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GPT-5.4 mini gives you the larger context window at 400K, compared with 128K for Mellum2-12B-A2.5B-Thinking.
GPT-5.4 mini is ahead on BenchLM's provisional leaderboard, 69 to 59. The biggest single separator in this matchup is GPQA, where the scores are 88% and 57.6%.
Mellum2-12B-A2.5B-Thinking has the edge for knowledge tasks in this comparison, averaging 57.6 versus 57.4. Inside this category, GPQA is the benchmark that creates the most daylight between them.
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