Head-to-head comparison across 1benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
Gemini 2.5 Pro
66
GPT-5.5 Pro
100
Pick GPT-5.5 Pro if you want the stronger benchmark profile. Gemini 2.5 Pro only becomes the better choice if you want the cheaper token bill or you would rather avoid the extra latency and token burn of a reasoning model.
Knowledge
+16.4 difference
Gemini 2.5 Pro
GPT-5.5 Pro
$1.25 / $10
$30 / $180
117 t/s
N/A
21.19s
N/A
1M
1M
Pick GPT-5.5 Pro if you want the stronger benchmark profile. Gemini 2.5 Pro only becomes the better choice if you want the cheaper token bill or you would rather avoid the extra latency and token burn of a reasoning model.
GPT-5.5 Pro is clearly ahead on the provisional aggregate, 100 to 66. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GPT-5.5 Pro's sharpest advantage is in knowledge, where it averages 57.2 against 40.8. The single biggest benchmark swing on the page is HLE, 18.8% to 57.2%.
GPT-5.5 Pro is also the more expensive model on tokens at $30.00 input / $180.00 output per 1M tokens, versus $1.25 input / $10.00 output per 1M tokens for Gemini 2.5 Pro. That is roughly 18.0x on output cost alone. GPT-5.5 Pro is the reasoning model in the pair, while Gemini 2.5 Pro is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use.
GPT-5.5 Pro is ahead on BenchLM's provisional leaderboard, 100 to 66. The biggest single separator in this matchup is HLE, where the scores are 18.8% and 57.2%.
GPT-5.5 Pro has the edge for knowledge tasks in this comparison, averaging 57.2 versus 40.8. Inside this category, HLE is the benchmark that creates the most daylight between them.
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