Head to head
Claude Fable 5.1 vs GPT-6 Astra
Which is better, Claude Fable 5.1 or GPT-6 Astra?
Claude Fable 5.1 finishes ahead of GPT-6 Astra on the index, 87.9 to 84.9, and leads on all four scores: craft, speed, control and value. Both are scored on the same rubric, in the same week, and neither placing is sponsored.
Updated
Claude Fable 5.1
08 of 73
87.9
Anthropic's top tier for the longest, hardest runs, with a cheaper Opus now snapping at its heels.
GPT-6 Astra
21 of 73
84.9
OpenAI's most capable model: a specialist for the hardest problems, priced like one.
The four scores, side by side
| Score | Claude Fable 5.1 | GPT-6 Astra | Difference |
|---|---|---|---|
| Craft | 95 | 91 | +4 |
| Speed | 76 | 72 | +4 |
| Control | 91 | 91 | — |
| Value | 72 | 70 | +2 |
| Index score | 87.9 | 84.9 | +3.0 |
Which to pick
Claude Fable 5.1 is the safer pick on every axis we score. GPT-6 Astra earns its place in the index, but nothing in these four numbers argues for it over Claude Fable 5.1.
Claude Fable 5.1
Fable 5.1 is Anthropic's most expensive model and the one it positions for demanding reasoning and long-horizon agent work. It is a clear step up from Fable 5 and cuts the price of cached input by three quarters, which matters on long runs that re-read the same context. The trouble is Opus 5.5, which arrived three weeks later, scores higher on both independent leaderboards and costs well under half as much. Fable now earns its place only on work where you have measured the difference.
Where it shines
- Built and priced for hours-long agent runs that must not drift
- Cached input costs a quarter of what it did on Fable 5
- Strong on computer-use and terminal benchmarks
GPT-6 Astra
Astra sits above the Sol and Luna tiers of GPT-6 and is the model OpenAI points at its most demanding work, with a million-token window and a long thinking budget. It ties for third on the Artificial Analysis index, but human voters rate it well below the cheaper GPT-6.1 Sol, and it shares the top price band in this index with Claude Fable 5.1. OpenAI rates its cyber capability as critical, which shapes what it will and will not do.
Where it shines
- OpenAI's strongest model on hard reasoning and mathematics
- Million-token context with a thinking budget you control
- Backed by the deepest tooling ecosystem of any lab