Pricing · Anthropic
Claude Mythos 5.1
Anthropic's claude-mythos-5-1, 1M tokens of context. Every number on this page was read off Anthropic's own pricing
page — never estimated, never recalled from memory.
Pricing
| Input | $10.00 | per 1M tokens |
|---|---|---|
| Output | $50.00 | per 1M tokens |
| Cached input | $0.25 | per 1M tokens · 0.025× the input price |
| Cache write (5 min TTL) | $12.50 | per 1M tokens |
| Cache write (1 h TTL) | $20.00 | per 1M tokens |
| Batch API | −50% | off input and output · verified September 16, 2026 against Anthropic's pricing page |
At the calculator's starting volume, 1M input tokens and 200K output tokens with no cache hits, Claude Mythos 5.1 costs $20.00: $10.00 for input and $10.00 for output, at the prices above. Same formula as the calculator; change the volume there.
Where this price sits
$10.00 per 1M input tokens is the 62nd cheapest input price of the 67 current models with a verified price on this site, and the 11th of Anthropic's 14. Output costs 5.0× the input price.
Other current models in the Mythos family:
- Claude Mythos 5 1M tokens $10.00 in · $50.00 out
Other price lists Anthropic publishes for Claude Mythos 5.1
The prices above are Anthropic's Standard list, the one the table and the calculator use. Anthropic also sells Claude Mythos 5.1 on one other list, each with a condition. Figures and wording are quoted from Anthropic's own pages as read on the date shown; this site computes none of them.
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Batch · 50% discount on both input and output tokens · wait: results when the batch completes or after 24 hours
Printed for Claude Mythos 5.1: $5.00 input, $25.00 output, per 1M tokens.
The Batch API allows asynchronous processing of large volumes of requests with a 50% discount on both input and output tokens.
You can access batch results when all messages have completed or after 24 hours, whichever comes first.
Source, read September 16, 2026
Mentioned in
One post on this site cites Claude Mythos 5.1. The sentence is the post's own, taken from where it links here.
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Prompt Caching Is Not 10% Everywhere: What a Cache Hit Costs Across Eight Providers · September 16, 2026
Claude Fable 5.1 and Claude Mythos 5.1 both cost $10.00 per million input tokens and $0.25 per million cached, a quarter of what the rule would give.
Against Claude Mythos 5
Claude Mythos 5 is the earlier version of the same name in this dataset (still current). Against Claude Mythos 5, Claude Mythos 5.1 has the same input price ($10.00); the same output price ($50.00); cached input at $0.25 against $1.00, 4× less (per 1M tokens). Its prices were verified September 28, 2026: Claude Mythos 5 pricing →
Specifications
| API model id | claude-mythos-5-1 | |
|---|---|---|
| Provider | Anthropic | |
| Family | Mythos | |
| Context window | 1M tokens | |
| Max output | 128K tokens | |
| Released | September 1, 2026 | |
| Status | Current | |
| Access | invite-only — Invite-only, through Project Glasswing | |
| Earliest retirement | Not before September 1, 2027 — no firm date announced | |
Claude Mythos 5.1 was released on September 1, 2026. It returns up to 128K tokens per response, against a context window of 1M tokens. Anthropic has committed not to retire it before September 1, 2027; no firm date is announced.
Questions about Claude Mythos 5.1 pricing
- How much does Claude Mythos 5.1 cost per million tokens?
- $10.00 per 1M input tokens and $50.00 per 1M output tokens, read on Anthropic's model page on September 28, 2026.
- What does a cached input token cost on Claude Mythos 5.1?
- $0.25 per 1M cached input tokens, 2.5% of the $10.00 input price; a 5-minute cache write costs $12.50, a 1-hour cache write costs $20.00 per 1M tokens.
Verified by hand on 2026-09-21 against the model overview page this row cites, which prints 'Input pricing $10 / MTok' and 'Output pricing $50 / MTok' and, in its Pricing block, 'Input $10 / MTok', 'Output $50 / MTok', '5m cache write $12.50 / MTok', '1h cache write $20 / MTok' and 'Cache read $0.25 / MTok'. Until September 15, 2026 that page printed only the input and output prices; the cache prices (hit $0.25, 5-minute write $12.50, 1-hour write $20) were read then from Anthropic's general pricing page, whose footnote states that cache hits on Claude Fable 5.1 and Claude Mythos 5.1 are priced at 0.025x the base input price. The batch discount also comes from that general pricing page, not from the overview page this row cites: Batch API discount (batchDiscount 0.5) verified by hand on 2026-09-16 against Anthropic's general pricing page, 'Batch processing' section: 'The Batch API allows asynchronous processing of large volumes of requests with a 50% discount on both input and output tokens', table row 'Claude Mythos 5.1 ( limited availability ) $5 / MTok $25 / MTok'.
Verified September 28, 2026 against Anthropic's model page. Confidence: confirmed. Cache prices verified September 15, 2026 against Anthropic's pricing page. No price change recorded for this model. How the data is checked.
Other Anthropic models with a verified price
- Claude Haiku 4.5 Haiku $1.00 in · $5.00 out
- Claude Sonnet 5.5 Sonnet $2.00 in · $10.00 out
- Claude Sonnet 5 Sonnet $2.00 in · $10.00 out
- Claude Sonnet 4.6 Sonnet $3.00 in · $15.00 out
- Claude Opus 5.5 Opus $4.00 in · $20.00 out
- Claude Opus 5 Opus $5.00 in · $25.00 out
- Claude Opus 4.8 Opus $5.00 in · $25.00 out
- Claude Opus 4.7 Opus $5.00 in · $25.00 out
- Claude Opus 4.6 Opus $5.00 in · $25.00 out
- Claude Opus 4.5 Opus $5.00 in · $25.00 out
- Claude Fable 5.1 Fable $10.00 in · $50.00 out
- Claude Fable 5 Fable $10.00 in · $50.00 out
- Claude Mythos 5 Mythos $10.00 in · $50.00 out
Cheaper or equally priced alternatives
Current models with an input price at or below $10.00 per 1M tokens.
- GPT-6 Astra OpenAI $10.00 in · $50.00 out
- Claude Fable 5.1 Anthropic $10.00 in · $50.00 out
- Claude Fable 5 Anthropic $10.00 in · $50.00 out
- Claude Mythos 5 Anthropic $10.00 in · $50.00 out
Compare every model in one table →
Work out what this costs at your volume →