Head-to-head comparison across 2benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
Claude Sonnet 5
94
Mellum2-12B-A2.5B-Instruct
26
Pick Claude Sonnet 5 if you want the stronger benchmark profile. Mellum2-12B-A2.5B-Instruct only becomes the better choice if you would rather avoid the extra latency and token burn of a reasoning model.
Coding
+26.0 difference
Knowledge
+16.5 difference
Claude Sonnet 5
Mellum2-12B-A2.5B-Instruct
$3 / $15
N/A
N/A
N/A
N/A
N/A
1M
128K
Pick Claude Sonnet 5 if you want the stronger benchmark profile. Mellum2-12B-A2.5B-Instruct only becomes the better choice if you would rather avoid the extra latency and token burn of a reasoning model.
Claude Sonnet 5 is clearly ahead on the provisional aggregate, 94 to 26. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
Claude Sonnet 5's sharpest advantage is in coding, where it averages 63.2 against 37.2.
Claude Sonnet 5 is the reasoning model in the pair, while Mellum2-12B-A2.5B-Instruct is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use. Claude Sonnet 5 gives you the larger context window at 1M, compared with 128K for Mellum2-12B-A2.5B-Instruct.
Claude Sonnet 5 is ahead on BenchLM's provisional leaderboard, 94 to 26.
Claude Sonnet 5 has the edge for knowledge tasks in this comparison, averaging 57.4 versus 40.9. Mellum2-12B-A2.5B-Instruct stays close enough that the answer can still flip depending on your workload.
Claude Sonnet 5 has the edge for coding in this comparison, averaging 63.2 versus 37.2. Mellum2-12B-A2.5B-Instruct stays close enough that the answer can still flip depending on your workload.
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