Claude Mythos 5 vs Gemini 3 Pro

Pick Claude Mythos 5 if you want the stronger benchmark profile. Gemini 3 Pro only becomes the better choice if you want the cheaper token bill or you need the larger 2M context window.

Claude Mythos 5 is clearly ahead on the provisional aggregate, 99 to 80. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

Claude Mythos 5's sharpest advantage is in multimodal & grounded, where it averages 92.7 against 81.1. The single biggest benchmark swing on the page is CharXiv, 93.5% to 81.4%.

Claude Mythos 5 is also the more expensive model on tokens at $10.00 input / $50.00 output per 1M tokens, versus $2.00 input / $12.00 output per 1M tokens for Gemini 3 Pro. That is roughly 4.2x on output cost alone. Claude Mythos 5 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. Gemini 3 Pro gives you the larger context window at 2M, compared with 1M+ for Claude Mythos 5.