Claude Mythos 5.1 wins more areas, narrowly.
Scores updated · 15 tests both models report · How we compare
Where each one wins
Tests won in each of the two 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.
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 tests each model wins by the widest margin, up to three each. Scores are out of 100.
Where Claude Mythos 5.1 pulls ahead
- Very hard expert questions across many subjectsHumanity's Last Exam+1.8points ahead
Where Claude Fable 5.1 pulls ahead
No clear win on a test scored out of 100.
Every test, side by side
All 15 tests both models report. The winning score is in its model's colour; marks a score checked independently.
ReasoningClaude Mythos 5.1
- Humanity's Last ExamClaude Mythos 5.1 by 1.859.160.9+1.8
- ARC-AGI-2tie9090tie
Other results11 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.
- Terminal-Bench 4.0Claude Mythos 5.1 by 5.155.860.9+5.1
- ARC-AGI-1tie97.597.5tie
- DeepSWE 1.1tie67.467.4tie
- GDPval-AA v2tie18531853tie
- HealthBench Professionaltie62.162.1tie
- HLE (with tools)tie6565tie
- OSWorld 2.0 (partial)tie77.977.9tie
- OSWorld 2.0 (strict)tie41.741.7tie
- Program Benchtie87.687.6tie
- SWE-bench Multimodaltie54.754.7tie
- Terminal-Bench-Science 0.1tie52.652.6tie
Questions people ask
Which is better, Claude Fable 5.1 or Claude Mythos 5.1?
Claude Mythos 5.1 wins one of the two areas where both have results: reasoning. Claude Fable 5.1 wins none. They are level on coding.
Which is better for coding?
Neither. All 2 coding tests both models report are ties.
Which is cheaper?
Claude Fable 5.1 costs $10.00 per million input tokens and $50.00 per million output tokens; Claude Mythos 5.1 costs $10.00 and $50.00. For a million tokens read plus a million written, they cost about the same.
How do you compare the two?
We use the 15 benchmark tests both models have published scores on. The verdict counts the 4 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 11 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.