Claude Mythos 5.1
by Anthropic
Today's price · per 1M tokens
Input
$10.00
per 1M tokens
Output
$50.00
per 1M tokens
Blended
$20.00
blended $/1M — 3:1 weighted input:output
Cached input
$0.250
3% of input — prompt caching
How this price is scoped: Cache hits and refreshes on Claude Mythos 5.1 (and Claude Fable 5.1) are priced at 0.025x the base input price — $0.25 per 1M tokens — where every other Claude model uses the standard 0.1x multiplier. Base $10/$50 per 1M tokens; Batch API $5/$25. Verified 2026-09-01 against platform.claude.com/docs/en/about-claude/pricing.
Price receipt
We read Anthropic's own pricing page on Sep 1, 2026 and found Claude Mythos 5.1 ([limited availability](https://anthropic. listed with a price on the same row — that read is where the number above comes from, recorded as a new model. We keep the page text we read; its content hash is e3310d2553.
Overview
Anthropic Claude Mythos 5.1 — the limited-availability counterpart to Claude Fable 5.1, offered to approved organizations through the Glasswing program. Same rate card: $10/$50 per 1M tokens, cache hits $0.25 per 1M tokens (0.025x input).
Capabilities
struck through = not supportedBenchmark performance
accuracy % · higher is better- Ranks #60 of 75 benchmarked models by average score
- Ranks #84 of 174 comparably-measured models by percentile score, across 3 independent measurements
- Ranks #165 of 174 comparably-tested models by normalized performance per dollar
- Strongest at Humanity's Last Exam — 65%, #2 of 56
Source: Vellum LLM Leaderboard · updated Sep 1, 2026 · See full rankings →
Specifications
- Provider
- Anthropic
- Context window
- 1M tokens
- Modality
- text, image
- Parameters
- Proprietary
- Open source
- No — proprietary
- Released
- Sep 1, 2026
- Status
- Current
- Last updated
- Sep 1, 2026
- Tags
Availability verified: Sep 1, 2026 — listed on Anthropic's own page