GPT-6 Astra vs Claude Fable 5.1
Head-to-head technical comparison of intelligence, capabilities, and API pricing.
Which should you use?
GPT-6 Astra and Claude Fable 5.1 score within 0.2 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 8 points, inside the confidence intervals the public board reports, so human preference does not separate them.
Pick GPT-6 Astra when
On these measures GPT-6 Astra 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.
Pick Claude Fable 5.1 when
- Stronger on MMLU-Pro: 95.9% against 95.8%.
Value per point of measured capability, at list input pricing: GPT-6 Astra $0.103 · Claude Fable 5.1 $0.103 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.
Our reporting on OpenAI and Anthropic
OpenAI's Private Safety Processing Targets Anthropic's 30-Day Retention Gap
OpenAI previews Private Safety Processing, cross-session abuse detection with zero data retention, directly countering Anthropic's 30-day covered-model policy.
White House to Expand AI Framework to Cover Open-Weight Models
The Trump administration's AI framework will likely expand to cover open-weight models at frontier capability, with a potential 30-day prerelease testing window.
Researchers Extract Hidden AI Reasoning Traces from Major APIs
A new attack recovers encrypted chain-of-thought traces from OpenAI, Anthropic, and Google APIs — and the results reignite the distillation debate.