Claude Mythos Preview vs o3-mini

Pick Claude Mythos Preview if you want the stronger benchmark profile. o3-mini only becomes the better choice if knowledge is the priority or you want the cheaper token bill.

Claude Mythos Preview is clearly ahead on the aggregate, 84 to 65. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

Claude Mythos Preview's sharpest advantage is in coding, where it averages 83.8 against 49.3. The single biggest benchmark swing on the page is SWE-bench Verified, 93.9% to 49.3%. o3-mini does hit back in knowledge, so the answer changes if that is the part of the workload you care about most.

Claude Mythos Preview is also the more expensive model on tokens at $25.00 input / $125.00 output per 1M tokens, versus $1.10 input / $4.40 output per 1M tokens for o3-mini. That is roughly 28.4x on output cost alone. Claude Mythos Preview gives you the larger context window at 1M, compared with 200K for o3-mini.