Head-to-head comparison across 1benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
GPT-5.3 Codex
89
GPT-5.5 Pro
100
Pick GPT-5.5 Pro if you want the stronger benchmark profile. GPT-5.3 Codex only becomes the better choice if you want the cheaper token bill.
Agentic
+18.6 difference
GPT-5.3 Codex
GPT-5.5 Pro
$1.75 / $14
$30 / $180
79 t/s
N/A
88.26s
N/A
400K
1M
Pick GPT-5.5 Pro if you want the stronger benchmark profile. GPT-5.3 Codex 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 89. 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 71.5.
GPT-5.5 Pro is also the more expensive model on tokens at $30.00 input / $180.00 output per 1M tokens, versus $1.75 input / $14.00 output per 1M tokens for GPT-5.3 Codex. That is roughly 12.9x on output cost alone. GPT-5.5 Pro gives you the larger context window at 1M, compared with 400K for GPT-5.3 Codex.
GPT-5.5 Pro is ahead on BenchLM's provisional leaderboard, 100 to 89.
GPT-5.5 Pro has the edge for agentic tasks in this comparison, averaging 90.1 versus 71.5. GPT-5.3 Codex stays close enough that the answer can still flip depending on your workload.
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