Claude Mythos 5.1
Anthropic · Released 1 Sep 2026 · claude-mythos-5-1
$10.00
Input price / 1M tokens
$50.00
Output price / 1M tokens
1M
Context window
#29 of 71
–
Output tokens / second
60.9%
Terminal-Bench 4.0
#3 of 10
Summary
Claude Mythos 5.1 is a proprietary model from Anthropic, released on 1 Sep 2026.
Its 1M-token context window ranks #29 of 71.
The Claude Fable 5.1 model offered by invitation only to Project Glasswing participants, with safeguards designed to support cybersecurity and life-sciences work. Shares Fable 5.1's specifications and pricing.
Benchmarks · 1 reported
| Benchmark | Score | Bar | Rank | Source |
|---|---|---|---|---|
| Terminal-Bench 4.0agentic coding | 60.9% | #3 of 10 | Anthropic Fable 5.1 / Mythos 5.1 launch postSelf-reported |
Self-reported means the lab ran the test itself. A rank appears only where several labs report the same version of a benchmark.
Similar models
Models with the most benchmarks in common with Claude Mythos 5.1, and the closest scores.
Terminal-Bench 4.0
#3 of 10Long jobs in a real terminal
- Claude Mythos 5.160.9
- GPT-6 Astra57.9
- Claude Fable 5.155.8
- Claude Opus 5.566.4
- Claude Opus 552.3
- Claude Sonnet 5.570.6
Compare Claude Mythos 5.1 side by side
Pre-filled with the two closest models. Swap any of them.
Sources
- price, cache prices, batch, limited availability: platform.claude.com/docs/en/about-claude/pricing, checked 2 Oct 2026
- context, max output, release, api id, knowledge cutoff, invite-only status, platforms: platform.claude.com/docs/en/models/mythos-5-1/overview, checked 2 Oct 2026
- status, retirement commitment (not sooner than 2027-09-01): platform.claude.com/docs/en/about-claude/model-deprecations, checked 2 Oct 2026
- minimum cacheable prompt length: platform.claude.com/docs/en/build-with-claude/prompt-caching, checked 2 Oct 2026
- benchmarks: anthropic.com/claude-fable-and-mythos-5-1, checked 2 Oct 2026
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