Head-to-head comparison across 3benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
Claude Mythos Preview
99
GPT-5.4 nano
63
Verified leaderboard positions: Claude Mythos Preview #1 · GPT-5.4 nano unranked
Pick Claude Mythos Preview if you want the stronger benchmark profile. GPT-5.4 nano only becomes the better choice if you want the cheaper token bill.
Agentic
+39.5 difference
Knowledge
+21.7 difference
Multimodal
+26.6 difference
Claude Mythos Preview
GPT-5.4 nano
$25 / $125
$0.2 / $1.25
N/A
191 t/s
N/A
3.64s
1M
400K
Pick Claude Mythos Preview if you want the stronger benchmark profile. GPT-5.4 nano only becomes the better choice if you want the cheaper token bill.
Claude Mythos Preview is clearly ahead on the provisional aggregate, 99 to 63. 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 agentic, where it averages 82.4 against 42.9. The single biggest benchmark swing on the page is OSWorld-Verified, 79.6% to 39%.
Claude Mythos Preview is also the more expensive model on tokens at $25.00 input / $125.00 output per 1M tokens, versus $0.20 input / $1.25 output per 1M tokens for GPT-5.4 nano. That is roughly 100.0x on output cost alone. Claude Mythos Preview gives you the larger context window at 1M, compared with 400K for GPT-5.4 nano.
Claude Mythos Preview is ahead on BenchLM's provisional leaderboard, 99 to 63. The biggest single separator in this matchup is OSWorld-Verified, where the scores are 79.6% and 39%.
Claude Mythos Preview has the edge for knowledge tasks in this comparison, averaging 74.9 versus 53.2. Inside this category, HLE w/o tools is the benchmark that creates the most daylight between them.
Claude Mythos Preview has the edge for agentic tasks in this comparison, averaging 82.4 versus 42.9. Inside this category, OSWorld-Verified is the benchmark that creates the most daylight between them.
Claude Mythos Preview has the edge for multimodal and grounded tasks in this comparison, averaging 92.7 versus 66.1. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.
For engineers, researchers, and the plain curious — a weekly brief on new models, ranking shifts, and pricing changes.
Free. No spam. Unsubscribe anytime.