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overview changedmodels/mythos-5/overview

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11---
22title: Claude Mythos 5
33url: https://platform.claude.com/docs/en/models/mythos-5/overview
4description: "Claude Mythos 5 reference: the same model as Claude Fable 5, offered for defensive cybersecurity work to organizations verified through Anthropic's verification programs. Model IDs, specifications, pricing, and migration resources. Claude Mythos 5.1 is the current Mythos model."
4description: "Claude Mythos 5 reference: the same model as Claude Fable 5, offered for defensive cybersecurity work to organizations verified through Anthropic's verification programs. Model IDs, specifications, pricing, and migration resources. Claude Mythos 5.2 is the current Mythos model."
55---
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77**Verification required.** Released June 9, 2026.
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2020 
2121| Model | Context | Max output | Price / MTok | Thinking | Default effort | Knowledge cutoff |
2222| :---------------------------------------------------------------------------------- | :------ | :--------- | :----------------- | :------------------- | :------------- | :--------------- |
23| [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) | 1M | 128K | $10 / $50 | Adaptive (always on) | `high` | Jun 2026 |
23| [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview) | 1M | 128K | $8 / $40 | Adaptive (always on) | `high` | Jun 2026 |
2424| **Claude Mythos 5** (this model) | 1M | 128K | $10 / $50 | Adaptive (always on) | `high` | Jan 2026 |
2525| [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview) | 1M | 128K | $4 / $20 | Adaptive (always on) | `medium` | Jun 2026 |
2626| [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview) | 1M | 128K | $2 / $10 | Adaptive | `high` | Jun 2026 |
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2828 
2929* **Context:** 1M tokens is roughly 555k words or 2.5M Unicode characters on the current tokenizer (introduced with Claude Opus 4.7); models before it fit about 750k words in 1M tokens. 200k tokens is roughly 150k words.
3030* **Max output:** Synchronous Messages API limit. On the Message Batches API, Claude Opus 5.5, Claude Opus 5, Claude Sonnet 5.5, Claude Sonnet 5, Claude Haiku 5.5, Claude Opus 4.8, Claude Opus 4.7, Claude Opus 4.6, and Claude Sonnet 4.6 support up to 300k output tokens with the output-300k-2026-03-24 beta header.
31* **Price / MTok:** Input / output, base price per million tokens. Batch API requests are 50% off; prompt caching reads cost 10% of the base input price (2.5% on Claude Fable 5.1 and Claude Mythos 5.1, 5% on Claude Opus 5.5 and Claude Sonnet 5.5). See Pricing for the full list.
31* **Price / MTok:** Input / output, base price per million tokens. Batch API requests are 50% off; prompt caching reads cost 10% of the base input price (2.5% on Claude Fable 5.2, Claude Mythos 5.2, Claude Fable 5.1, and Claude Mythos 5.1, 5% on Claude Opus 5.5 and Claude Sonnet 5.5). See Pricing for the full list.
3232* **Thinking:** Adaptive thinking lets the model decide how much to think, steered by effort. Extended thinking is the manual budget\_tokens mode on earlier models.
3333* **Default effort:** The effort parameter’s default on the Claude API. Models without a value don’t support the parameter.
3434* **Knowledge cutoff:** Reliable knowledge cutoff: the date through which the model’s knowledge is most extensive and reliable.
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8181## Resources
8282 
8383<CardGroup cols={3}>
84 <Card title="Migrate to Claude Mythos 5.1" icon="arrows-left-right" href="https://platform.claude.com/docs/en/models/fable-5-1/migration-guide#migrating-from-claude-mythos-5-to-claude-mythos-5-1">
85 What changes when moving from Claude Mythos 5 to Claude Mythos 5.1.
84 <Card title="Migrate to Claude Mythos 5.2" icon="arrows-left-right" href="https://platform.claude.com/docs/en/models/fable-5-2/migration-guide#migrating-from-claude-mythos-5-to-claude-mythos-5-2">
85 What changes when moving from Claude Mythos 5 to Claude Mythos 5.2.
8686 </Card>
8787 
88 <Card title="Claude Mythos 5.1" icon="arrow-right" href="https://platform.claude.com/docs/en/models/mythos-5-1/overview">
88 <Card title="Claude Mythos 5.2" icon="arrow-right" href="https://platform.claude.com/docs/en/models/mythos-5-2/overview">
8989 The current Mythos model: overview, specs, and resources.
9090 </Card>
9191</CardGroup>
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