# Claude Fable 5.1

> Claude Fable 5.1 is Anthropic's successor to Claude Fable 5 for long-running agentic coding, knowledge work and research, released September 1, 2026. It has a 1M-token context window and costs $10 / $50 per 1M input/output tokens, the same as Fable 5, with cache reads cut to $0.25. In Claude Code you pick it explicitly with the `fable` alias.

URL: https://aistack.sh/model/claude-fable-5-1
Vendor: Anthropic (product page: https://aistack.sh/tool/claude)
Last checked against sources: 2026-09-24

## Specs

- Released: Sep 1, 2026
- Status: Available
- API model ID: claude-fable-5-1
- API price (in / out): $10 / $50 per 1M tokens
- Cache read: $0.25 per 1M tokens
- Context window: 1M tokens
- Plans: Pro (usage credits), Max, Team premium, Enterprise
- Platforms: Claude API, Amazon Bedrock, Claude Platform on AWS, Google Cloud, Microsoft Foundry

## Where you can use it

- Claude (https://aistack.sh/tool/claude): Not on Free. Pro reaches it through usage credits; Max and Team premium seats can spend up to 50% of their weekly limits on it.
- Claude Code (https://aistack.sh/tool/claude-code): Select it with the `fable` alias (Claude Code v2.1.257 or later). It is not the default on any plan or provider.

## Comparisons

- [Claude Fable 5.1 vs Claude Opus 5.5](https://aistack.sh/compare/claude-fable-5-1-vs-claude-opus-5-5)

## FAQ

### How much does Claude Fable 5.1 cost on the API?

$10 per 1M input tokens and $50 per 1M output tokens, the same as Claude Fable 5. Cache reads are $0.25 per 1M tokens.

### How do I use Claude Fable 5.1 in Claude Code?

Select it with the `fable` alias, for example `/model fable`. It needs Claude Code v2.1.257 or later and is never the default, so you have to choose it.

### Is Claude Fable 5.1 on the free Claude plan?

No. Claude's pricing page gives Pro access through usage credits, and lets Max and Team premium seats spend up to 50% of their weekly limits on Fable.

### What is the Claude Fable 5.1 context window?

1M tokens by default, with 128k max output tokens and always-on adaptive thinking.

## Sources

- [Claude Developer Platform release notes](https://platform.claude.com/docs/en/release-notes/overview), read 2026-09-24
- [Claude API pricing](https://platform.claude.com/docs/en/about-claude/pricing), read 2026-09-24
- [Claude models overview](https://platform.claude.com/docs/en/about-claude/models/overview), read 2026-09-24
- [Claude Code model configuration](https://code.claude.com/docs/en/model-config), read 2026-09-24
- [Claude plans and pricing](https://claude.com/pricing), read 2026-09-24