Head-to-head comparison across 3benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
Claude Mythos Preview
99
Grok 4.3
79
Verified leaderboard positions: Claude Mythos Preview #1 · Grok 4.3 unranked
Pick Claude Mythos Preview if you want the stronger benchmark profile. Grok 4.3 only becomes the better choice if you want the cheaper token bill.
Coding
+36.5 difference
Knowledge
+21.0 difference
Multimodal
+14.3 difference
Claude Mythos Preview
Grok 4.3
$25 / $125
$1.25 / $2.5
N/A
209 t/s
N/A
12.36s
1M
1M
Pick Claude Mythos Preview if you want the stronger benchmark profile. Grok 4.3 only becomes the better choice if you want the cheaper token bill.
Claude Mythos Preview is clearly ahead on the provisional aggregate, 99 to 79. 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 coding, where it averages 83.8 against 47.3. The single biggest benchmark swing on the page is HLE, 64.7% to 35%.
Claude Mythos Preview is also the more expensive model on tokens at $25.00 input / $125.00 output per 1M tokens, versus $1.25 input / $2.50 output per 1M tokens for Grok 4.3. That is roughly 50.0x on output cost alone.
Claude Mythos Preview is ahead on BenchLM's provisional leaderboard, 99 to 79. The biggest single separator in this matchup is HLE, where the scores are 64.7% and 35%.
Claude Mythos Preview has the edge for knowledge tasks in this comparison, averaging 74.9 versus 53.9. 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 47.3. Grok 4.3 stays close enough that the answer can still flip depending on your workload.
Claude Mythos Preview has the edge for multimodal and grounded tasks in this comparison, averaging 92.4 versus 78.1. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.
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