Head-to-head comparison across 3 benchmark categories
Claude Mythos Preview
84
GPT-5.4 mini
68
Pick Claude Mythos Preview if you want the stronger benchmark profile. GPT-5.4 mini only becomes the better choice if you want the cheaper token bill.
Agentic
+15.3 difference
Knowledge
+33.4 difference
Multimodal
+16.1 difference
Claude Mythos Preview
GPT-5.4 mini
$25 / $125
$0.75 / $4.5
N/A
201 t/s
N/A
3.85s
1M
400K
Pick Claude Mythos Preview if you want the stronger benchmark profile. GPT-5.4 mini only becomes the better choice if you want the cheaper token bill.
Claude Mythos Preview is clearly ahead on the aggregate, 84 to 68. 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 knowledge, where it averages 74.9 against 41.5. The single biggest benchmark swing on the page is HLE w/o tools, 56.8% to 28.2%.
Claude Mythos Preview is also the more expensive model on tokens at $25.00 input / $125.00 output per 1M tokens, versus $0.75 input / $4.50 output per 1M tokens for GPT-5.4 mini. That is roughly 27.8x on output cost alone. Claude Mythos Preview gives you the larger context window at 1M, compared with 400K for GPT-5.4 mini.
Claude Mythos Preview is ahead overall, 84 to 68. The biggest single separator in this matchup is HLE w/o tools, where the scores are 56.8% and 28.2%.
Claude Mythos Preview has the edge for knowledge tasks in this comparison, averaging 74.9 versus 41.5. 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 80.9 versus 65.6. Inside this category, Terminal-Bench 2.0 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 76.6. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.
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