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Legacy. Released June 9, 2026.
Although Claude Fable 5 is still available, you should consider migrating to Claude Fable 5.1 for improved performance. See Claude Fable 5.1 · Migrate to Claude Fable 5.1
Model ID: claude-fable-5
Context window: 1M tokens · Max output: 128K tokens · Input pricing: $10 / MTok · Output pricing: $50 / MTok
Fable vs. Mythos
Claude Mythos 5 is offered separately, by invitation only, for defensive cybersecurity workflows as part of Project Glasswing. It shares Claude Fable 5's specifications and pricing; Claude Fable 5 includes safety classifiers that can decline requests, and Claude Mythos 5 does not. For access, contact your Anthropic, AWS, or Google Cloud account team.
How it compares to the current lineup
| Model | Context | Max output | Price / MTok | Thinking | Default effort | Knowledge cutoff |
|---|---|---|---|---|---|---|
| Claude Fable 5.1 | 1M | 128K | $10 / $50 | Adaptive (always on) | high | Jun 2026 |
| Claude Fable 5 (this model) | 1M | 128K | $10 / $50 | Adaptive (always on) | high | Jan 2026 |
| Claude Opus 5 | 1M | 128K | $5 / $25 | Adaptive | high | May 2026 |
| Claude Sonnet 5 | 1M | 128K | $2 / $10 | Adaptive | high | Jan 2026 |
| Claude Haiku 4.5 | 200K | 64K | $1 / $5 | Extended | — | Feb 2025 |
- 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.
- Max output: Synchronous Messages API limit. On the Message Batches API, Claude Opus 5, Claude Sonnet 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.
- 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). See Pricing for the full list.
- 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.
- Default effort: The effort parameter’s default on the Claude API. Models without a value don’t support the parameter.
- Knowledge cutoff: Reliable knowledge cutoff: the date through which the model’s knowledge is most extensive and reliable.
Specifications
Model IDs
| Platform | Model ID |
|---|---|
| Claude API | claude-fable-5 |
| Amazon Bedrock | anthropic.claude-fable-5 |
| Google Cloud | claude-fable-5 |
| Microsoft Foundry | claude-fable-5 |
| Claude Platform on AWS | claude-fable-5 |
Pricing
| Feature | Value |
|---|---|
| Input | $10 / MTok |
| Output | $50 / MTok |
| 5m cache write | $12.50 / MTok |
| 1h cache write | $20 / MTok |
| Cache read | $1 / MTok |
| Batch API | 50% discount on input and output |
| Full price list | Pricing |
Capabilities
| Feature | Value |
|---|---|
| Context window | 1M tokens |
| Max output | 128K tokens |
| Thinking | Adaptive (always on) |
| Default effort | high |
| Input → output | Text and images → text |
| Reliable knowledge cutoff | Jan 2026 |
| Training data cutoff | Jan 2026 |
Availability
| Feature | Value |
|---|---|
| Status | Active (legacy) |
| Released | June 9, 2026 |
| Retirement | Not sooner than June 9, 2027 |
| Platforms | Claude API, Amazon Bedrock, Google Cloud, Microsoft Foundry, Claude Platform on AWS |
Resources
What changes when moving from Claude Fable 5 to Claude Fable 5.1.
The current Fable model: overview, specs, and resources.
Capabilities, API changes, and availability for Claude Fable 5.
Model-specific prompting guidance for long-horizon and agentic work.
Handle classifier refusals and retry on another Claude model with the `fallbacks` parameter.
Reference
The system prompt Claude Fable 5 uses on claude.ai and the Claude apps.
Safety evaluations and deployment decisions for Claude Fable 5 and Claude Mythos 5.
Full price list, including batch discounts and prompt caching rates.
How model IDs, aliases, and pinned snapshots work.
Lifecycle status and retirement commitments for every Claude model.