Claude Fable 5.1

Anthropic · Multimodal · Released Sep 2026

Claude Fable 5.1 is Anthropic's most capable reasoning model, an incremental improvement over Claude Fable 5 with a 1M token context window.

Strengths: Excels at agentic coding, long-running autonomous workflows, and knowledge work including complex code refactors and visual tasks.
Best for: Extended reasoning problems, autonomous software development, multi-step agentic work, and tasks requiring sustained reasoning over large documents or codebases.
Limitations: Slower and more expensive than Claude Sonnet 5; use Claude Opus 5 if you need even stronger reasoning for the most complex multi-step problems requiring maximum capability.

Input / 1M

$10.00

Output / 1M

$50.00

Cached input / 1M

$0.25

Context window

Also billed

Price history

Effective	Input	Output	Cached in	Note	Source
1 Sep 2026	$10.00	$50.00	$0.25	Imported from OpenRouter	openrouter.ai

Claude Fable 5.1 (batch)

in $5.00 · out $25.00

Claude Opus 5

in $5.00 · out $25.00

Claude Opus 5 (batch)

in $2.50 · out $12.50

Claude Sonnet 5

in $2.00 · out $10.00

Data updated Sep 1, 2026 Report a problem