Claude Fable 5.1 vs Claude Fable 5
Head-to-head technical comparison of intelligence, capabilities, and API pricing.
Which should you use?
Claude Fable 5.1 and Claude Fable 5 score within 0.5 points of each other on the composite index, which is too close to call a winner on capability alone.
Their Arena Elo differs by only 3 points, inside the confidence intervals the public board reports, so human preference does not separate them.
Pick Claude Fable 5.1 when
- Stronger on MMLU-Pro: 95.9% against 95.6%.
Pick Claude Fable 5 when
On these measures Claude Fable 5 does not lead Claude Fable 5.1 anywhere, so pick it only for reasons outside this table — an existing integration, a region, or a contract.
Value per point of measured capability, at list input pricing: Claude Fable 5.1 $0.103 · Claude Fable 5 $0.104 per index point. Run your own token mix through the token cost calculator — a comparison at list price ignores caching and batch discounts, which move real bills more than this gap does.
Where these numbers come from
Figures as of 2026-09-07. Arena Elo and pricing are read from the public board and each vendor's own pricing page; see the full leaderboard for all 34 models and which columns are measured rather than estimated, or the benchmark matrix for scores benchmark by benchmark.