Claude Haiku 5.5 vs Claude Fable 5.1

Pyyan / Compare / Claude Haiku 5.5 vs Claude Fable 5.1

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Language Models · verified 10 Oct 2026

Claude Haiku 5.5Anthropiccurrent

Claude Fable 5.1Anthropiccurrent

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Specification	Claude Haiku 5.5	Claude Fable 5.1
Summary	A tenth of Haiku 4.5's price, and it finishes terminal tasks Haiku 4.5 could not start.	Same price as Fable 5, and cache reads cost a quarter of what they did.
Context	Not published	1M
Input ($/Mtok)	$0.1	$10
Output ($/Mtok)	$0.5	$50
Licence	Proprietary	Proprietary
Max output	Not published	128K
Parameters	Not published	Not published
Released	7 Oct 2026	1 Sep 2026
Model ID	claude-haiku-5-5	claude-fable-5-1
Category	Language Models	Language Models
Official	Anthropic ↗	—

Highlighted rows are where these differ.

39.2% on Terminal-Bench 4.0, where Haiku 4.5 scored 0.0%
Above 100K tokens the price rises to $0.50 and $2.50, for the whole request
First Haiku with an adjustable effort setting, and a new tokenizer that spends slightly more tokens

Best for high volume work at the bottom of the stack.

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.