Head-to-head comparison across 4 benchmark categories
Claude Mythos Preview
84
Kimi K2.5
72
Pick Claude Mythos Preview if you want the stronger benchmark profile. Kimi K2.5 only becomes the better choice if you want the cheaper token bill or you would rather avoid the extra latency and token burn of a reasoning model.
Agentic
+26.3 difference
Coding
+21.4 difference
Knowledge
+9.8 difference
Multimodal
+14.2 difference
Claude Mythos Preview
Kimi K2.5
$25 / $125
$0.5 / $2.8
N/A
45 t/s
N/A
2.38s
1M
128K
Pick Claude Mythos Preview if you want the stronger benchmark profile. Kimi K2.5 only becomes the better choice if you want the cheaper token bill or you would rather avoid the extra latency and token burn of a reasoning model.
Claude Mythos Preview is clearly ahead on the aggregate, 84 to 72. 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 80.9 against 54.6. The single biggest benchmark swing on the page is HLE, 64.7% to 30.1%.
Claude Mythos Preview is also the more expensive model on tokens at $25.00 input / $125.00 output per 1M tokens, versus $0.50 input / $2.80 output per 1M tokens for Kimi K2.5. That is roughly 44.6x on output cost alone. Claude Mythos Preview is the reasoning model in the pair, while Kimi K2.5 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. Claude Mythos Preview gives you the larger context window at 1M, compared with 128K for Kimi K2.5.
Claude Mythos Preview is ahead overall, 84 to 72. The biggest single separator in this matchup is HLE, where the scores are 64.7% and 30.1%.
Claude Mythos Preview has the edge for knowledge tasks in this comparison, averaging 74.9 versus 65.1. Inside this category, HLE is the benchmark that creates the most daylight between them.
Claude Mythos Preview has the edge for coding in this comparison, averaging 83.8 versus 62.4. 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 54.6. 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 78.5. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.
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