Head-to-head comparison across 5benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
Gemini 3.5 Flash
81
GPT-5.5
78
Verified leaderboard positions: Gemini 3.5 Flash #9 · GPT-5.5 #6
Pick Gemini 3.5 Flash if you want the stronger benchmark profile. GPT-5.5 only becomes the better choice if reasoning is the priority.
Agentic
+4.3 difference
Coding
+4.1 difference
Reasoning
+10.3 difference
Knowledge
+8.4 difference
Multimodal
+13.4 difference
Gemini 3.5 Flash
GPT-5.5
$1.5 / $9
$5 / $30
284.2 t/s
N/A
18.55s
N/A
1M
1M
Pick Gemini 3.5 Flash if you want the stronger benchmark profile. GPT-5.5 only becomes the better choice if reasoning is the priority.
Gemini 3.5 Flash has the cleaner provisional overall profile here, landing at 81 versus 78. It is a real lead, but still close enough that category-level strengths matter more than the headline number.
Gemini 3.5 Flash's sharpest advantage is in multimodal & grounded, where it averages 83.8 against 70.4. The single biggest benchmark swing on the page is ARC-AGI-2, 72.1% to 85%. GPT-5.5 does hit back in reasoning, 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 $1.50 input / $9.00 output per 1M tokens for Gemini 3.5 Flash. That is roughly 3.3x on output cost alone.
Gemini 3.5 Flash is ahead on BenchLM's provisional leaderboard, 81 to 78. The biggest single separator in this matchup is ARC-AGI-2, where the scores are 72.1% and 85%.
GPT-5.5 has the edge for knowledge tasks in this comparison, averaging 66.4 versus 58. Inside this category, AA-Omniscience Hallucination Rate is the benchmark that creates the most daylight between them.
GPT-5.5 has the edge for coding in this comparison, averaging 58.6 versus 54.5. Inside this category, AA Coding Index is the benchmark that creates the most daylight between them.
GPT-5.5 has the edge for reasoning in this comparison, averaging 85 versus 74.7. Inside this category, CritPt is the benchmark that creates the most daylight between them.
GPT-5.5 has the edge for agentic tasks in this comparison, averaging 81.5 versus 77.2. Inside this category, GDPval-AA is the benchmark that creates the most daylight between them.
Gemini 3.5 Flash has the edge for multimodal and grounded tasks in this comparison, averaging 83.8 versus 70.4. Inside this category, AA-MMMU-Pro is the benchmark that creates the most daylight between them.
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