Claude Mythos 5.1 at a glance.
From Anthropic's own pages, read Oct 20, 2026, so company-reported. A token is a word or part of a word. Prices can change; check the maker's page before you build on them.
- Made by
- AnthropicBased in US
- Released
- Sep 1, 2026Anthropic: Claude Mythos product page
- What it is for
- “Our most capable model for cybersecurity and biology research.”Anthropic: Claude Mythos product page, Oct 20, 2026 · in Anthropic's words
- Reads at once
- Not statedIts context window: how much text it can take in one go
- Takes in
- Not stated
- Download
- No, online only
Anthropic shows no public price for it.
No public per-token price found. Mythos page: 'Claude Mythos 5.1 is available to vetted cyberdefenders and life scientists through our trusted access programs.'
Anthropic: Claude Mythos product page, Oct 20, 2026 · company-reported
Where it ranks.
Its position on each of the 21 tests the models page uses, by testers other than the maker. Epoch AI's and Vectara's scores are shown under their open licenses; for LMArena, Scale and Vals we give the position and link to their own leaderboard. Each list is a snapshot with its date.
| Test | Rank | Score |
|---|---|---|
| Epoch Capabilities IndexEpoch AI, Oct 20, 2026 | Not in the top 30 | |
| Vals IndexVals AI, Oct 19, 2026 | Not in the top 20 |
| Test | Rank | Score |
|---|---|---|
| LMArena WebDevLMArena, Oct 19, 2026 | Not in the top 20 | |
| SWE-Bench ProScale AI, Sep 22, 2026 | Not in the top 16 | |
| Vibe Code BenchVals AI, Oct 18, 2026 | Not in the top 20 | |
| LMArena coding chatsLMArena, Oct 15, 2026 | Not in the top 20 |
| Test | Rank | Score |
|---|---|---|
| LMArena textLMArena, Oct 15, 2026 | Not in the top 20 | |
| LMArena creative writingLMArena, Oct 15, 2026 | Not in the top 20 | |
| MultiChallengeScale AI, Feb 3, 2026 | Not in the top 15 |
| Test | Rank | Score |
|---|---|---|
| LMArena Agent ArenaLMArena, Oct 19, 2026 | Not in the top 20 | |
| Remote Labor IndexScale AI | Not in the top 16 | |
| Terminal-Bench 4.0Vals AI, Oct 19, 2026 | Not in the top 20 | |
| CUA-bench (games)Vals AI, Oct 13, 2026 | Not in the top 9 |
| Test | Rank | Score |
|---|---|---|
| LMArena mathLMArena, Oct 15, 2026 | Not in the top 20 | |
| Humanity's Last ExamScale AI | Not in the top 17 | |
| ProofBenchVals AI, Oct 12, 2026 | Not in the top 20 |
| Test | Rank | Score |
|---|---|---|
| LMArena visionLMArena, Oct 19, 2026 | Not in the top 20 | |
| LMArena documentsLMArena, Sep 13, 2026 | Not in the top 20 |
| Test | Rank | Score |
|---|---|---|
| GPQA DiamondVals AI, Sep 1, 2026 | Not in the top 20 | |
| MMMU ProVals AI, Sep 1, 2026 | Not in the top 20 |
| Test | Rank | Score |
|---|---|---|
| Vectara hallucination testVectara, Oct 16, 2026 | Not in our copy of the list |
“Not in the top” means it isn't among the models in our copy of that list, which runs to the position shown; it may not have been tested. Vectara's test ranks by how rarely a model adds facts, so lower is better. Positions can be shared when scores tie. Epoch's range is its margin of uncertainty. Epoch AI and Vectara data: CC BY 4.0 and Apache-2.0.
What Claude costs.
Anthropic's chat app, priced by the month in US dollars on its own pages. Which plans include Claude Mythos 5.1 is on Anthropic's pages.
Every chat app's plans| Plan | A month |
|---|---|
| Free | Free |
| Pro | $20 |
| Max | from $100 |
| Team (Standard seat) | $25 a seat |
| Team (Premium seat) | $125 a seat |
| Enterprise | $20 a seat + usage |
Anthropic pricing page, Oct 20, 2026 · company-reported
Our note: Restricted access, not generally available. Anthropic: 'Claude Fable 5.1 and Claude Mythos 5.1 are the same underlying model'; announcement blurb: 'Access remains limited to a small set of vetted organizations.' Context and input types not separately stated for Mythos; left empty.