Head-to-head comparison across 2benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
GPT-5.4 nano
62
GPT-5.5 Pro
100
Pick GPT-5.5 Pro if you want the stronger benchmark profile. GPT-5.4 nano only becomes the better choice if you want the cheaper token bill.
Agentic
+47.2 difference
Knowledge
+4.0 difference
GPT-5.4 nano
GPT-5.5 Pro
$0.2 / $1.25
$30 / $180
191 t/s
N/A
3.64s
N/A
400K
1M
Pick GPT-5.5 Pro if you want the stronger benchmark profile. GPT-5.4 nano only becomes the better choice if you want the cheaper token bill.
GPT-5.5 Pro is clearly ahead on the provisional aggregate, 100 to 62. 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 agentic, where it averages 90.1 against 42.9. The single biggest benchmark swing on the page is HLE, 37.7% 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 $0.20 input / $1.25 output per 1M tokens for GPT-5.4 nano. That is roughly 144.0x on output cost alone. GPT-5.5 Pro gives you the larger context window at 1M, compared with 400K for GPT-5.4 nano.
GPT-5.5 Pro is ahead on BenchLM's provisional leaderboard, 100 to 62. The biggest single separator in this matchup is HLE, where the scores are 37.7% and 57.2%.
GPT-5.5 Pro has the edge for knowledge tasks in this comparison, averaging 57.2 versus 53.2. Inside this category, HLE is the benchmark that creates the most daylight between them.
GPT-5.5 Pro has the edge for agentic tasks in this comparison, averaging 90.1 versus 42.9. GPT-5.4 nano stays close enough that the answer can still flip depending on your workload.
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