Head-to-head comparison across 1benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
Claude 3.5 Sonnet
42
GPT-5.5 Pro
100
Pick GPT-5.5 Pro if you want the stronger benchmark profile. Claude 3.5 Sonnet only becomes the better choice if knowledge is the priority or you want the cheaper token bill.
Knowledge
+2.2 difference
Claude 3.5 Sonnet
GPT-5.5 Pro
$3 / $15
$30 / $180
N/A
N/A
N/A
N/A
200K
1M
Pick GPT-5.5 Pro if you want the stronger benchmark profile. Claude 3.5 Sonnet 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 42. 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 $3.00 input / $15.00 output per 1M tokens for Claude 3.5 Sonnet. That is roughly 12.0x on output cost alone. GPT-5.5 Pro is the reasoning model in the pair, while Claude 3.5 Sonnet 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 gives you the larger context window at 1M, compared with 200K for Claude 3.5 Sonnet.
GPT-5.5 Pro is ahead on BenchLM's provisional leaderboard, 100 to 42.
Claude 3.5 Sonnet has the edge for knowledge tasks in this comparison, averaging 59.4 versus 57.2. GPT-5.5 Pro stays close enough that the answer can still flip depending on your workload.
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