Claude Fable 5.1
Anthropic · released Sep 1, 2026
| size | huge, not disclosed by the manufacturer |
| context window | 1,000,000 tokens |
| longest response | 128,000 tokens |
| knowledge cutoff | June 2026 |
| open weights | no |
| API price | $10 per million input tokens, $50 per million output tokens |
| input and output | text and images in, text out |
Manufacturer data (announcement, documentation, pricing), verified Sep 25, 2026.
Where we tested it
The silence test
TaskThe model had to stay quiet for a moment; the correct reply had zero characters.
It stayed silent once in six tries. Other times it replied with at least one word, “Dobře.” (Czech for “Okay.”), or acted the silence out along with an explanation of why complete silence was impossible.
Dragon
TaskThe model's task was to draw a picture of a dragon as an SVG.
Two dragons worth 39 and 30 points out of 50, 2nd and a shared 12th place among 34.
You'll find the size band and figures for other models on the Tested models page.