Claude Mythos Preview vs Claude Opus 4.6

Pick Claude Opus 4.6 if you want the stronger benchmark profile. Claude Mythos Preview only becomes the better choice if agentic is the priority or you want the stronger reasoning-first profile.

Claude Opus 4.6 finishes one point ahead overall, 85 to 84. That is enough to call, but not enough to treat as a blowout. This matchup comes down to a few meaningful edges rather than one model dominating the board.

Claude Opus 4.6's sharpest advantage is in knowledge, where it averages 91.3 against 74.9. The single biggest benchmark swing on the page is Terminal-Bench 2.0, 82% to 65.4%. Claude Mythos Preview does hit back in agentic, 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 $15.00 input / $75.00 output per 1M tokens for Claude Opus 4.6. Claude Mythos Preview is the reasoning model in the pair, while Claude Opus 4.6 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.