Claude Mythos Preview vs Claude Opus 5
Wins 2 of 4 areas
Reasoning · Images and charts
Wins 2 of 4 areas
Coding · Agents
The two are evenly matched.Claude Mythos Preview is better at reasoning and images and charts; Claude Opus 5 at coding and agents.
Scores updated · 12 tests both models report · How we compare
Where each one wins
Tests won in each of the four areas where both have results. Each piece is one test, so a longer bar means more evidence; grey means the two scored within a point of each other.
- CodingWriting and fixing software03Claude Opus 53 of 3 tests
- AgentsCarrying out multi-step tasks on its own02Claude Opus 52 of 2 tests
- ReasoningHard problems that need careful thinking20Claude Mythos Preview2 of 2 tests
- Images and chartsUnderstanding pictures, charts and video10Claude Mythos Preview1 of 1 test
Images and charts rests on a single test.
What it costs
Prices per million tokens, roughly 750,000 words. The bars show the cost of a million tokens read plus a million written.
The biggest differences
The three tests each model wins by the widest margin. Scores are out of 100.
Where Claude Opus 5 pulls ahead
- Finds hard-to-locate facts by browsing the webBrowseComp+3.9points ahead
- Completes tasks by operating a computer desktopOSWorld-Verified+3.8points ahead
- Fixes real GitHub issues in many programming languagesSWE-bench Multilingual+2.2points ahead
Where Claude Mythos Preview pulls ahead
- Very hard expert questions across many subjectsHumanity's Last Exam+9.8points ahead
- Reasoning about charts from research papersCharXiv (RQ)+9.5points ahead
- Graduate-level biology, physics and chemistry questionsGPQA Diamond+1.4points ahead
Every test, side by side
All 12 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingClaude Opus 5
- SWE-bench MultilingualClaude Opus 5 by 2.287.389.5+2.2
- SWE-bench VerifiedClaude Opus 5 by 2.193.996+2.1
- SWE-bench ProClaude Opus 5 by 1.477.879.2+1.4
AgentsClaude Opus 5
- BrowseCompClaude Opus 5 by 3.986.990.8+3.9
- OSWorld-VerifiedClaude Opus 5 by 3.879.683.4+3.8
ReasoningClaude Mythos Preview
- Humanity's Last ExamClaude Mythos Preview by 9.864.754.9+9.8
- GPQA DiamondClaude Mythos Preview by 1.494.693.2+1.4
Images and chartsClaude Mythos Preview
- CharXiv (RQ)Claude Mythos Preview by 9.593.283.7+9.5
Other results4 tests, not counted
Tests outside the eight areas. They are not counted above: several are summary scores built from other tests, or the same test under another name.
- HealthBenchClaude Opus 5 by 661.167.1+6
- HealthBench ProfessionalClaude Mythos Preview by 4.964.759.8+4.9
- HLE (with tools)Claude Mythos Preview by 1.164.763.6+1.1
- SWE-bench Multimodaltie5959.4tie
Questions people ask
Which is better, Claude Mythos Preview or Claude Opus 5?
Claude Mythos Preview and Claude Opus 5 each win two of the four areas where both have results. Claude Mythos Preview wins reasoning and images and charts; Claude Opus 5 wins coding and agents.
Which is better for coding?
Claude Opus 5. It wins 3 of the 3 coding tests both models report; Claude Mythos Preview wins none.
How do you compare the two?
We use the 12 benchmark tests both models have published scores on. The verdict counts the 8 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 4 are listed but not counted, because several are summary scores or repeat a test. Each score is the one shown on the model's own page.