AI Models & Releases
Claude Fable 5.1 Explained: Price, Changes and the Ban Story
Anthropic released Claude Fable 5.1 on September 1, 2026 at the same base prices as Fable 5, with a lower running cost for long tasks and fewer false alarms from its safety filters. Here is what changed, what it costs, and how the June 2026 export controls on Fable 5 began and ended.
Key takeaways
- Anthropic released Claude Fable 5.1 on September 1, 2026 at the same input and output prices as Fable 5: $10 and $50 per million tokens.
- Cache reads fell 75 percent to $0.25 per million tokens, which Anthropic estimates lowers total cost by about 25 percent for typical workloads and up to about 45 percent for agent-heavy work.
- Mythos 5.1 is the same model with looser safeguards and is limited to vetted organizations through Anthropic's verification programs.
- Claude Opus 5.5, released on September 22, 2026, costs $4 and $20 per million tokens and, by Anthropic's account, matches Fable 5.1 on most work.
- US export controls kept Fable 5 offline from June 12 to July 1, 2026, after Amazon researchers reported a way around its safety filters, and the Commerce Department withdrew them on June 30, 2026.
Claude Fable 5.1 is an AI model that Anthropic released on September 1, 2026. It follows Fable 5 at the same base prices, and Anthropic says it costs less to run on long tasks. Anthropic describes it as its most capable model open to all customers. This article explains what changed, what Fable 5.1 costs, and how it relates to Mythos 5.1 and Claude Opus 5.5. It also explains why a US government order took Fable 5 offline for 19 days in June 2026.