Head-to-head comparison across 4benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
Gemini 3.5 Flash
87
GPT-5.4 Pro
91
Verified leaderboard positions: Gemini 3.5 Flash #6 · GPT-5.4 Pro unranked
Pick GPT-5.4 Pro if you want the stronger benchmark profile. Gemini 3.5 Flash only becomes the better choice if knowledge is the priority or you want the cheaper token bill.
Agentic
+12.1 difference
Reasoning
+8.6 difference
Knowledge
+9.0 difference
Multimodal
+10.2 difference
Gemini 3.5 Flash
GPT-5.4 Pro
$1.5 / $9
$30 / $180
284.2 t/s
74 t/s
18.55s
151.79s
1M
1.05M
Pick GPT-5.4 Pro if you want the stronger benchmark profile. Gemini 3.5 Flash only becomes the better choice if knowledge is the priority or you want the cheaper token bill.
GPT-5.4 Pro is clearly ahead on the provisional aggregate, 91 to 87. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GPT-5.4 Pro's sharpest advantage is in agentic, where it averages 89.3 against 77.2. The single biggest benchmark swing on the page is HLE, 40.2% to 58.7%. Gemini 3.5 Flash does hit back in knowledge, so the answer changes if that is the part of the workload you care about most.
GPT-5.4 Pro is also the more expensive model on tokens at $30.00 input / $180.00 output per 1M tokens, versus $1.50 input / $9.00 output per 1M tokens for Gemini 3.5 Flash. That is roughly 20.0x on output cost alone. GPT-5.4 Pro gives you the larger context window at 1.05M, compared with 1M for Gemini 3.5 Flash.
GPT-5.4 Pro is ahead on BenchLM's provisional leaderboard, 91 to 87. The biggest single separator in this matchup is HLE, where the scores are 40.2% and 58.7%.
Gemini 3.5 Flash has the edge for knowledge tasks in this comparison, averaging 58 versus 49. Inside this category, HLE is the benchmark that creates the most daylight between them.
GPT-5.4 Pro has the edge for reasoning in this comparison, averaging 83.3 versus 74.7. Inside this category, ARC-AGI-2 is the benchmark that creates the most daylight between them.
GPT-5.4 Pro has the edge for agentic tasks in this comparison, averaging 89.3 versus 77.2. Gemini 3.5 Flash stays close enough that the answer can still flip depending on your workload.
GPT-5.4 Pro has the edge for multimodal and grounded tasks in this comparison, averaging 94 versus 83.8. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.
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