Claude Fable 5.1
Anthropic's most powerful generally available model, released September 1, 2026. Built for long agent runs, research and heavy document, spreadsheet and slide work.
- Made by
- Anthropic
- Released
- Type
- Flagship
- Status
- Live
- How to get it
- Claude apps (included on Max and premium Team seats; Pro and standard Team seats pay with usage credits) and the Claude API
- Good for
- Long agent tasksDeep researchSpreadsheets and slides
What it is
Fable sits above Opus as Anthropic’s top tier. Fable 5.1 replaced Fable 5 on September 1, 2026, and launched the same day as Claude Mythos 5.1, which is the same model with stricter access controls. It reads up to 1 million tokens at once and can write up to 128K tokens in one answer.
Anthropic says the biggest gains are in long-running coding agents, multi-step research, and work on documents, spreadsheets and slides.
What it costs
$10 per million input tokens and $50 per million output tokens in the API, the same as Fable 5. Cached input now costs a quarter of what it did, so Anthropic estimates typical bills about 25% lower, and up to about 45% lower for agent-heavy work.
In the Claude apps, Max plans include it. On Pro, you pay for it with usage credits.
What it means for you
For most everyday work, Anthropic itself suggests starting with Opus 5.5, which is cheaper. Reach for Fable 5.1 when a task is long and hard: a research report that pulls from dozens of sources, a big spreadsheet model, or a coding agent you leave running for an hour.
Use cases this model is good for
How to summarize a long PDF or contract with AI (without missing the important parts)
You have a 60-page report or contract and need the key points, numbers and risks today, without reading every page.
Best pick: ClaudeUp to 2h savedHow to automate a boring computer task with an AI-written script (no coding experience needed)
You do the same file-renaming or copy-paste job every week and suspect a small script could do it for you.
Best pick: ClaudeHours saved
