Head-to-head comparison across 3benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
Grok 4.3
75
Mellum2-12B-A2.5B-Instruct
27
Pick Grok 4.3 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
+10.1 difference
Knowledge
+13.0 difference
Inst. Following
+5.5 difference
Grok 4.3
Mellum2-12B-A2.5B-Instruct
$1.25 / $2.5
N/A
209 t/s
N/A
12.36s
N/A
1M
128K
Pick Grok 4.3 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.
Grok 4.3 is clearly ahead on the provisional aggregate, 75 to 27. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
Grok 4.3's sharpest advantage is in knowledge, where it averages 53.9 against 40.9. The single biggest benchmark swing on the page is GPQA, 90.1% to 40.9%.
Grok 4.3 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. Grok 4.3 gives you the larger context window at 1M, compared with 128K for Mellum2-12B-A2.5B-Instruct.
Grok 4.3 is ahead on BenchLM's provisional leaderboard, 75 to 27. The biggest single separator in this matchup is GPQA, where the scores are 90.1% and 40.9%.
Grok 4.3 has the edge for knowledge tasks in this comparison, averaging 53.9 versus 40.9. Inside this category, GPQA is the benchmark that creates the most daylight between them.
Grok 4.3 has the edge for coding in this comparison, averaging 47.3 versus 37.2. Mellum2-12B-A2.5B-Instruct stays close enough that the answer can still flip depending on your workload.
Grok 4.3 has the edge for instruction following in this comparison, averaging 81.3 versus 75.8. Mellum2-12B-A2.5B-Instruct stays close enough that the answer can still flip depending on your workload.
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