Head-to-head comparison across 3benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
DeepSeek V4 Flash (Max)
77
GPT-5.5
93
Verified leaderboard positions: DeepSeek V4 Flash (Max) #12 · GPT-5.5 #3
Pick GPT-5.5 if you want the stronger benchmark profile. DeepSeek V4 Flash (Max) only becomes the better choice if coding is the priority or you want the cheaper token bill.
Agentic
+18.5 difference
Coding
+15.1 difference
Knowledge
+6.4 difference
DeepSeek V4 Flash (Max)
GPT-5.5
$0.14 / $0.28
$5 / $30
N/A
N/A
N/A
N/A
1M
1M
Pick GPT-5.5 if you want the stronger benchmark profile. DeepSeek V4 Flash (Max) only becomes the better choice if coding is the priority or you want the cheaper token bill.
GPT-5.5 is clearly ahead on the provisional aggregate, 93 to 77. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GPT-5.5's sharpest advantage is in agentic, where it averages 81.8 against 63.3. The single biggest benchmark swing on the page is Terminal-Bench 2.0, 56.9% to 82.7%. DeepSeek V4 Flash (Max) does hit back in coding, so the answer changes if that is the part of the workload you care about most.
GPT-5.5 is also the more expensive model on tokens at $5.00 input / $30.00 output per 1M tokens, versus $0.14 input / $0.28 output per 1M tokens for DeepSeek V4 Flash (Max). That is roughly 107.1x on output cost alone.
GPT-5.5 is ahead on BenchLM's provisional leaderboard, 93 to 77. The biggest single separator in this matchup is Terminal-Bench 2.0, where the scores are 56.9% and 82.7%.
GPT-5.5 has the edge for knowledge tasks in this comparison, averaging 66.4 versus 60. Inside this category, HLE is the benchmark that creates the most daylight between them.
DeepSeek V4 Flash (Max) has the edge for coding in this comparison, averaging 73.7 versus 58.6. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.
GPT-5.5 has the edge for agentic tasks in this comparison, averaging 81.8 versus 63.3. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.
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