Head-to-head comparison across 3 benchmark categories
Claude Mythos Preview
84
GPT-5.4
82
Pick Claude Mythos Preview if you want the stronger benchmark profile. GPT-5.4 only becomes the better choice if you want the cheaper token bill or you need the larger 1.05M context window.
Agentic
+3.9 difference
Coding
+26.1 difference
Multimodal
+11.5 difference
Claude Mythos Preview
GPT-5.4
$25 / $125
$2.5 / $15
N/A
74 t/s
N/A
151.79s
1M
1.05M
Pick Claude Mythos Preview if you want the stronger benchmark profile. GPT-5.4 only becomes the better choice if you want the cheaper token bill or you need the larger 1.05M context window.
Claude Mythos Preview has the cleaner overall profile here, landing at 84 versus 82. It is a real lead, but still close enough that category-level strengths matter more than the headline number.
Claude Mythos Preview's sharpest advantage is in coding, where it averages 83.8 against 57.7. The single biggest benchmark swing on the page is SWE-bench Pro, 77.8% to 57.7%.
Claude Mythos Preview is also the more expensive model on tokens at $25.00 input / $125.00 output per 1M tokens, versus $2.50 input / $15.00 output per 1M tokens for GPT-5.4. That is roughly 8.3x on output cost alone. GPT-5.4 gives you the larger context window at 1.05M, compared with 1M for Claude Mythos Preview.
Claude Mythos Preview is ahead overall, 84 to 82. The biggest single separator in this matchup is SWE-bench Pro, where the scores are 77.8% and 57.7%.
Claude Mythos Preview has the edge for coding in this comparison, averaging 83.8 versus 57.7. Inside this category, SWE-bench Pro 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 77. 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 81.2. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.
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