Claude Mythos 5.1 is the stronger all-rounder.
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+5.4points ahead
- Fixes real GitHub issues in many programming languagesSWE-bench Multilingual+2.5points ahead
- Long, multi-file coding tasks in real codebasesSWE-bench Pro+1.2points ahead
Where Claude Fable 5 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.
CodingClaude Mythos 5.1
- SWE-bench MultilingualClaude Mythos 5.1 by 2.586.689.1+2.5
- SWE-bench ProClaude Mythos 5.1 by 1.28081.2+1.2
ReasoningClaude Mythos 5.1
- Humanity's Last ExamClaude Mythos 5.1 by 5.455.560.9+5.4
- ARC-AGI-2tie89.290tie
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-Science 0.1Claude Mythos 5.1 by 27.924.752.6+27.9
- Terminal-Bench 4.0Claude Mythos 5.1 by 16.444.560.9+16.4
- GDPval-AA v2Claude Mythos 5.1 by 130 rating points17231853+130 rating
- OSWorld 2.0 (strict)Claude Mythos 5.1 by 5.636.141.7+5.6
- OSWorld 2.0 (partial)Claude Mythos 5.1 by 572.977.9+5
- HealthBench ProfessionalClaude Fable 5 by 3.96662.1+3.9
- DeepSWE 1.1Claude Fable 5 by 2.67067.4+2.6
- Program BenchClaude Mythos 5.1 by 1.386.387.6+1.3
- HLE (with tools)Claude Mythos 5.1 by 1.263.865+1.2
- ARC-AGI-1Claude Fable 5 by 198.597.5+1
- SWE-bench Multimodaltie54.154.7tie
Questions people ask
Which is better, Claude Fable 5 or Claude Mythos 5.1?
Claude Mythos 5.1 wins all two areas where both have results: coding and reasoning. Claude Fable 5 wins none.
Which is better for coding?
Claude Mythos 5.1. It wins 2 of the 2 coding tests both models report; Claude Fable 5 wins none.
Which is cheaper?
Claude Fable 5 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.