Gemini 3 Pro vs Grok 4.20

Pick Gemini 3 Pro if you want the stronger benchmark profile. Grok 4.20 only becomes the better choice if reasoning is the priority or you want the cheaper token bill.

Gemini 3 Pro is clearly ahead on the provisional aggregate, 81 to 73. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

Gemini 3 Pro's sharpest advantage is in multimodal & grounded, where it averages 81.1 against 70.8. The single biggest benchmark swing on the page is ARC-AGI-2, 31.1% to 53.3%. Grok 4.20 does hit back in reasoning, so the answer changes if that is the part of the workload you care about most.

Gemini 3 Pro is also the more expensive model on tokens at $2.00 input / $12.00 output per 1M tokens, versus $2.00 input / $6.00 output per 1M tokens for Grok 4.20. That is roughly 2.0x on output cost alone. Grok 4.20 is the reasoning model in the pair, while Gemini 3 Pro 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.