Head-to-head comparison across 1benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
GPT-5.5 Pro
100
o1
59
Pick GPT-5.5 Pro if you want the stronger benchmark profile. o1 only becomes the better choice if knowledge is the priority or you want the cheaper token bill.
Knowledge
+18.5 difference
GPT-5.5 Pro
o1
$30 / $180
$15 / $60
N/A
98 t/s
N/A
32.29s
1M
200K
Pick GPT-5.5 Pro if you want the stronger benchmark profile. o1 only becomes the better choice if knowledge is the priority or you want the cheaper token bill.
GPT-5.5 Pro is clearly ahead on the provisional aggregate, 100 to 59. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GPT-5.5 Pro is also the more expensive model on tokens at $30.00 input / $180.00 output per 1M tokens, versus $15.00 input / $60.00 output per 1M tokens for o1. That is roughly 3.0x on output cost alone. GPT-5.5 Pro gives you the larger context window at 1M, compared with 200K for o1.
GPT-5.5 Pro is ahead on BenchLM's provisional leaderboard, 100 to 59.
o1 has the edge for knowledge tasks in this comparison, averaging 75.7 versus 57.2. GPT-5.5 Pro stays close enough that the answer can still flip depending on your workload.
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