Claude Opus 4.6 vs Claude Fable 5.1

Pyyan / Compare / Claude Opus 4.6 vs Claude Fable 5.1

2 of 5

Language Models · verified 2 Sept 2026

Claude Opus 4.6Anthropiccurrent

Claude Fable 5.1Anthropiccurrent

Add another3 slots left

Specification	Claude Opus 4.6	Claude Fable 5.1
Summary	Last Opus to accept sampling parameters.	Same price as Fable 5, and cache reads cost a quarter of what they did.
Context	1M	1M
Input ($/Mtok)	$5	$10
Output ($/Mtok)	$25	$50
Licence	Proprietary	Proprietary
Max output	128K	128K
Parameters	—	Not published
Released	—	1 Sep 2026
Model ID	claude-opus-4-6	claude-fable-5-1
Category	Language Models	Language Models
Official	Anthropic ↗	—

Highlighted rows are where these differ.

Last Opus to accept sampling parameters.

Best for legacy pins.

Matches or beats Fable 5 at low and medium effort, and pulls clear at high effort
Cache reads cut to 25% of the old price, so re-reading a long context got much cheaper
Identical model to Mythos 5.1 underneath; the difference is the safeguards

Best for coding and long-running work.