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Claude Fable 5.1

GA

Anthropic's current Fable-tier model and its most capable generally available Claude: 'For demanding reasoning and long-horizon agentic work'. Released September 1, 2026 ('Latest. Released September 1, 2026' on its model page); the deprecations table reads Active with a tentative retirement not sooner than September 1, 2027. Adaptive thinking always on (no extended thinking); effort defaults to high. 1M context, 128K max output. 5m cache write $12.50/MTok, 1h cache write $20/MTok; the cached_input field carries the cache-hit rate, which on this model is 2.5% of input ($0.25/MTok) instead of the usual 10%. Batch $5 in / $25 out. Reliable knowledge cutoff Jun 2026; training data cutoff Jun 2026. Available on the Claude API, Amazon Bedrock, Vertex AI, Microsoft Foundry and Claude Platform on AWS; the same model is offered by invitation as Claude Mythos 5.1. Supersedes Claude Fable 5, now a legacy model. Added 2026-10-02, a month after release: the delay is ours.

Claude Fable 5.1 by Anthropic costs $10 per 1M input tokens and $50 per 1M output tokens ($20/1M blended), with a 1M (1.000.000-token) context window. It is generally available (GA), with a knowledge cutoff of Jun 2026.

Last verified: 15 Oct 2026 · sourced from official provider documentation

Provider
Anthropic
Status
GA
Input price
$10 / 1M tokens
Output price
$50 / 1M tokens
Cached input
$0.25 / 1M tokens
Blended price
$20 / 1M tokens
Context window
1.000.000 tokens (1M)
Max output
128.000 tokens
Modality
text, image, vision
Open weights
No — API only
Knowledge cutoff
2026-06
Released
1 Sep 2026
API string
claude-fable-5-1

Source: Anthropic official documentation ↗

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FAQ

Claude Fable 5.1 — questions & answers

How much does Claude Fable 5.1 cost?

Claude Fable 5.1 is priced at $10 per 1M input tokens and $50 per 1M output tokens ($20/1M blended at a 3:1 input-to-output ratio), with cached input at $0.25 per 1M tokens.

What is the context window of Claude Fable 5.1?

Claude Fable 5.1 has a 1.000.000-token context window (1M), with up to 128.000 output tokens per request.

Is Claude Fable 5.1 deprecated?

No — Claude Fable 5.1 is generally available (GA) and not currently scheduled for deprecation or retirement in our tracker.

Does Claude Fable 5.1 support image or vision input?

Yes — Claude Fable 5.1 accepts image input. Listed modalities: text, image, vision.

Can I self-host Claude Fable 5.1?

No — Claude Fable 5.1 is proprietary. Its weights are not publicly released, so it is available only through Anthropic's API (or hosted partners), not for self-hosting.

What is the API model string for Claude Fable 5.1?

The API model identifier for Claude Fable 5.1 is "claude-fable-5-1" when calling Anthropic's API.

What is Claude Fable 5.1's knowledge cutoff?

Claude Fable 5.1's training knowledge cutoff is Jun 2026.