Head-to-head comparison across 2benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
Claude Sonnet 4.5
66
DeepSeek V4 Flash Base
31
Pick Claude Sonnet 4.5 if you want the stronger benchmark profile. DeepSeek V4 Flash Base only becomes the better choice if reasoning is the priority or you need the larger 1M context window.
Reasoning
+31.1 difference
Knowledge
+31.2 difference
Claude Sonnet 4.5
DeepSeek V4 Flash Base
$3 / $15
$null / $null
N/A
N/A
N/A
N/A
200K
1M
Pick Claude Sonnet 4.5 if you want the stronger benchmark profile. DeepSeek V4 Flash Base only becomes the better choice if reasoning is the priority or you need the larger 1M context window.
Claude Sonnet 4.5 is clearly ahead on the provisional aggregate, 66 to 31. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
Claude Sonnet 4.5's sharpest advantage is in knowledge, where it averages 83.4 against 52.2. DeepSeek V4 Flash Base does hit back in reasoning, so the answer changes if that is the part of the workload you care about most.
DeepSeek V4 Flash Base gives you the larger context window at 1M, compared with 200K for Claude Sonnet 4.5.
Claude Sonnet 4.5 is ahead on BenchLM's provisional leaderboard, 66 to 31.
Claude Sonnet 4.5 has the edge for knowledge tasks in this comparison, averaging 83.4 versus 52.2. DeepSeek V4 Flash Base stays close enough that the answer can still flip depending on your workload.
DeepSeek V4 Flash Base has the edge for reasoning in this comparison, averaging 44.7 versus 13.6. Claude Sonnet 4.5 stays close enough that the answer can still flip depending on your workload.
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