Head-to-head comparison across 2benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
Claude Fable 5
96
Mellum2-12B-A2.5B-Thinking
59
Verified leaderboard positions: Claude Fable 5 #2 · Mellum2-12B-A2.5B-Thinking unranked
Pick Claude Fable 5 if you want the stronger benchmark profile. Mellum2-12B-A2.5B-Thinking only becomes the better choice if its workflow or ecosystem matters more than the raw scoreboard.
Coding
+15.7 difference
Knowledge
+17.2 difference
Claude Fable 5
Mellum2-12B-A2.5B-Thinking
$10 / $50
N/A
N/A
N/A
N/A
N/A
1M+
128K
Pick Claude Fable 5 if you want the stronger benchmark profile. Mellum2-12B-A2.5B-Thinking only becomes the better choice if its workflow or ecosystem matters more than the raw scoreboard.
Claude Fable 5 is clearly ahead on the provisional aggregate, 96 to 59. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
Claude Fable 5's sharpest advantage is in knowledge, where it averages 74.8 against 57.6. The single biggest benchmark swing on the page is GPQA, 94.5% to 57.6%.
Claude Fable 5 gives you the larger context window at 1M+, compared with 128K for Mellum2-12B-A2.5B-Thinking.
Claude Fable 5 is ahead on BenchLM's provisional leaderboard, 96 to 59. The biggest single separator in this matchup is GPQA, where the scores are 94.5% and 57.6%.
Claude Fable 5 has the edge for knowledge tasks in this comparison, averaging 74.8 versus 57.6. Inside this category, GPQA is the benchmark that creates the most daylight between them.
Claude Fable 5 has the edge for coding in this comparison, averaging 85.6 versus 69.9. Mellum2-12B-A2.5B-Thinking stays close enough that the answer can still flip depending on your workload.
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