Inference
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Anthropic

Claude Mythos Preview

Claude Mythos Preview is a reasoning model from Anthropic in the Claude Mythos family. It has 2 scored results in 1 category. It has no index.

  • Closed weights
  • Reasoning
  • Input: text
  • Released 2026-04
UnrankedEnough results for an index.
IndexAll categories, out of 100.UnrankedMedian 51.0
CoverageIndex weight that has results.20%
SpeedOutput tokens per second.—Median 67/s
First tokenSeconds to the first output token.—Median 1.3 s
Input / 1MUS dollars per 1M input tokens.$25.00Median $0.60
Output / 1MUS dollars per 1M output tokens.$125.00Median $2.55
ContextMaximum tokens in one request.—Median 262K
EloLMArena rating and rank.—Median 1422

Capabilities

Index per category, out of 100.
Out of 100
AgenticMulti-step tasks with tools.2 counted69.1—
CodingCode writing and repair.None counted——
ReasoningLogic problems and puzzles.None counted——
MultimodalTasks with images and text.None counted——
KnowledgeFacts and expert knowledge.None counted——
MultilingualTasks in many languages.None counted——
InstructionTasks with strict prompt rules.None counted——
MathMath problems.None counted——

Results

2 counted
BenchmarkThe benchmark name.ResultThe score from the source.PlacePlace among results on this benchmark.
CyberGymAgentic83.1%14 / 29
ExploitGymAgentic17.5%15 / 23

Sources

BenchLMCC BY-NC 4.0

History

5 releases
Output / 1M$125.00 → $125.00
23 Oct 202612 Nov 2026

Questions

How much does Claude Mythos Preview cost?
$25.00 per 1M input tokens, $125.00 per 1M output tokens.
Is Claude Mythos Preview open source?
No. Its weights are not published.
When was Claude Mythos Preview released?
April 2026.

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