Head-to-head comparison across 3benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
GPT-5.5
91
Grok 4.3
75
Verified leaderboard positions: GPT-5.5 #5 · Grok 4.3 unranked
Pick GPT-5.5 if you want the stronger benchmark profile. Grok 4.3 only becomes the better choice if multimodal & grounded is the priority or you want the cheaper token bill.
Coding
+11.3 difference
Knowledge
+12.5 difference
Multimodal
+7.7 difference
GPT-5.5
Grok 4.3
$5 / $30
$1.25 / $2.5
N/A
209 t/s
N/A
12.36s
1M
1M
Pick GPT-5.5 if you want the stronger benchmark profile. Grok 4.3 only becomes the better choice if multimodal & grounded is the priority or you want the cheaper token bill.
GPT-5.5 is clearly ahead on the provisional aggregate, 91 to 75. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GPT-5.5's sharpest advantage is in knowledge, where it averages 66.4 against 53.9. The single biggest benchmark swing on the page is HLE, 52.2% to 35%. Grok 4.3 does hit back in multimodal & grounded, so the answer changes if that is the part of the workload you care about most.
GPT-5.5 is also the more expensive model on tokens at $5.00 input / $30.00 output per 1M tokens, versus $1.25 input / $2.50 output per 1M tokens for Grok 4.3. That is roughly 12.0x on output cost alone.
GPT-5.5 is ahead on BenchLM's provisional leaderboard, 91 to 75. The biggest single separator in this matchup is HLE, where the scores are 52.2% and 35%.
GPT-5.5 has the edge for knowledge tasks in this comparison, averaging 66.4 versus 53.9. Inside this category, AA-Omniscience Hallucination Rate is the benchmark that creates the most daylight between them.
GPT-5.5 has the edge for coding in this comparison, averaging 58.6 versus 47.3. Inside this category, Terminal-Bench Hard is the benchmark that creates the most daylight between them.
Grok 4.3 has the edge for multimodal and grounded tasks in this comparison, averaging 78.1 versus 70.4. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.
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