Grok 4.3 vs Claude Fable 5.1

Pyyan / Compare / Grok 4.3 vs Claude Fable 5.1

2 of 5

Language Models · verified 2 Sept 2026

Grok 4.3xAIcurrent

Claude Fable 5.1Anthropiccurrent

Add another3 slots left

Specification	Grok 4.3	Claude Fable 5.1
Summary	Cheapest long-context option in the family.	Same price as Fable 5, and cache reads cost a quarter of what they did.
Context	1M	1M
Input ($/Mtok)	$1.25	$10
Output ($/Mtok)	$2.5	$50
Licence	Proprietary	Proprietary
Max output	—	128K
Parameters	—	Not published
Released	—	1 Sep 2026
Model ID	grok-4.3	claude-fable-5-1
Category	Language Models	Language Models
Official	xAI ↗	—

Highlighted rows are where these differ.

Best for long context on a budget.

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.