Head-to-head comparison across 1benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
GPT-5.5 Pro
100
Grok 4.20
77
Pick GPT-5.5 Pro if you want the stronger benchmark profile. Grok 4.20 only becomes the better choice if you want the cheaper token bill or you need the larger 2M context window.
Agentic
+43.0 difference
GPT-5.5 Pro
Grok 4.20
$30 / $180
$2 / $6
N/A
233 t/s
N/A
10.33s
1M
2M
Pick GPT-5.5 Pro if you want the stronger benchmark profile. Grok 4.20 only becomes the better choice if you want the cheaper token bill or you need the larger 2M context window.
GPT-5.5 Pro is clearly ahead on the provisional aggregate, 100 to 77. 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 47.1.
GPT-5.5 Pro is also the more expensive model on tokens at $30.00 input / $180.00 output per 1M tokens, versus $2.00 input / $6.00 output per 1M tokens for Grok 4.20. That is roughly 30.0x on output cost alone. Grok 4.20 gives you the larger context window at 2M, compared with 1M for GPT-5.5 Pro.
GPT-5.5 Pro is ahead on BenchLM's provisional leaderboard, 100 to 77.
GPT-5.5 Pro has the edge for agentic tasks in this comparison, averaging 90.1 versus 47.1. Grok 4.20 stays close enough that the answer can still flip depending on your workload.
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