Anthropic's most powerful generally available model — a tier above Opus, bringing Mythos-class capability to the public. Fable 5.1 replaced Fable 5 on Sep 1, 2026 at the same $10/$50 per-token price, with cached input reads cut 75% to $0.25/1M.
Claude Fable 5.1 replaced Fable 5 on September 1, 2026, on the API, claude.ai, Claude Code, and Claude Cowork. Input and output pricing are unchanged at $10/$50 per 1M tokens; the only pricing change is cached input reads, cut 75% from $1.00 to $0.25 per 1M tokens (cache writes stay at $12.50). Plan availability is unchanged: Max and Team Premium keep Fable 5.1 included at up to 50% of the weekly limit on an ongoing basis, while Pro and Team Standard run it on usage credits only.
Claude Fable 5.1, released September 1, 2026, replaces the original Fable 5 (June 9, 2026) at the identical $10 input / $50 output per-1M-token price. The one pricing change is cache reads, cut 75% from $1.00 to $0.25 per 1M tokens — cache writes stay at $12.50. Anthropic treats it as a routine successor: existing usage automatically moves to 5.1, and Fable 5 is no longer served.
Fable 5.1 keeps Fable 5's role as Anthropic's answer to a question they had been sitting on: how to ship the capabilities of Mythos — the internal frontier model that made headlines before release — in a form the public can actually buy. It remains the first Claude model to sit above Opus in the lineup rather than replacing it, with the same 1M context window and 128K output ceiling as the model it replaced.
Three days after Fable 5's original launch, the rollout stopped. On June 12, 2026, a US government export-control directive ordered Anthropic to suspend all access to Fable 5 (and the restricted Claude Mythos 5) for every user, after researchers reported a jailbreak technique that could get the model to identify software vulnerabilities and produce exploit code. Anthropic complied immediately while publicly disagreeing with the order. It then deployed an improved safety classifier that blocks the reported technique in over 99% of cases; the Commerce Department's Center for AI Standards and Innovation reviewed the safeguards and lifted the controls on June 30. Access was restored globally on July 1, 2026, and ran without interruption through the September 1 upgrade to 5.1.
Fable 5.1 carries over the same plan split that took effect on Fable 5 on July 20, 2026: Max and Team Premium keep it included at up to 50% of the weekly limit on an ongoing basis, while Pro and Team Standard run it purely on usage credits at the standard $10/$50 API rate. The API and consumption-based Enterprise plans have full access at the standard $10/$50 per-token rates (cache reads $0.25).
Anthropic describes Fable 5.1's capabilities as exceeding any model it has ever made generally available, with state-of-the-art results on nearly all tested benchmarks — software engineering, knowledge work, vision, and scientific research in particular. Early testers consistently call it a clear step beyond Opus 5 on complex, long-horizon reasoning and autonomous problem-solving: the multi-hour agentic tasks where prior models drift.
One unusual design choice: requests touching restricted high-risk areas — cybersecurity, biology and chemistry, model distillation — are automatically routed to Opus 5 instead, with a notice when that happens. In practice you get an answer from a still-frontier model rather than a refusal. The familiar Claude caveat also applies: no image, video, or audio generation.
| Model | Input / 1M | Output / 1M | Context |
|---|---|---|---|
| Claude Fable 5.1 | $10 | $50 | 1M |
| Claude Opus 5 | $5 | $25 | 1M |
| Claude Sonnet 5 | $2 | $10 | 1M |
| GPT-6 Astra | $10 | $50 | 1M |
| GPT-5.5 pro | $30 | $180 | 1M |
The pricing logic: Fable 5.1 costs 2× Opus 5 and matches OpenAI's new GPT-6 Astra exactly at $10/$50 — but sits at a third of GPT-5.5 pro's input rate and well under a third of its output rate, while claiming a strong benchmark record. If your task runs fine on Opus 5 or Sonnet 5, stay there; reach for Fable 5.1 when the task is genuinely hard, long, or expensive to get wrong. Since July 24, 2026, that bar is higher: Opus 5 delivers nearly all of Fable 5.1's intelligence at half the price.