Which is cheaper, Claude Fable 5.1 or Claude Opus 5?

Claude Fable 5.1 lists at $10 input / $50 output per 1M tokens; Claude Opus 5 lists at $5 input / $25 output per 1M tokens. Claude Opus 5 has the lower list price.

Which is used more, Claude Fable 5.1 or Claude Opus 5?

Claude Fable 5.1, with 2.8% of the AI-written code reviewed by cubic in the week of Nov 2, 2026, against 0.5% for Claude Opus 5.

Updated Nov 9, 2026

Claude Fable 5.1 vs Claude Opus 5

Claude Opus 5 is no longer ranked because it now writes under 0.5% of AI-attributed lines.

Claude Fable 5.1 and Claude Opus 5 compared on relative bug rate and on price and usage.
Bug rate
	Claude Fable 5.1	Claude Opus 5
Relative bug rate	0.88	No longer ranked
Details
Provider	Anthropic	Anthropic
Released	Sep 1, 2026	Jul 24, 2026
List price	$10 input / $50 output per 1M tokens	$5 input / $25 output per 1M tokens
Share of AI-written code, week of Nov 2	2.8%	0.5%

1.00 = average · lower is better

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Questions and answers

Which has fewer bugs, Claude Fable 5.1 or Claude Opus 5?: Claude Opus 5 is no longer ranked because it now writes under 0.5% of AI-attributed lines.
Which is cheaper, Claude Fable 5.1 or Claude Opus 5?: Claude Fable 5.1 lists at $10 input / $50 output per 1M tokens; Claude Opus 5 lists at $5 input / $25 output per 1M tokens. Claude Opus 5 has the lower list price.
Which is used more, Claude Fable 5.1 or Claude Opus 5?: Claude Fable 5.1, with 2.8% of the AI-written code reviewed by cubic in the week of Nov 2, 2026, against 0.5% for Claude Opus 5.