Pyyan / Compare / GPT-5.6 Luna vs Claude Fable 5.1
GPT-5.6 Luna vs Claude Fable 5.1
2 of 5Language Models · verified 2 Sept 2026
GPT-5.6 LunaOpenAIcurrentClaude Fable 5.1Anthropiccurrent
| Specification | GPT-5.6 Luna | Claude Fable 5.1 |
|---|---|---|
| Summary | Fastest and cheapest GPT-5.6 tier. | Same price as Fable 5, and cache reads cost a quarter of what they did. |
| Context | 1M+ | 1M |
| Input ($/Mtok) | — | $10 |
| Output ($/Mtok) | — | $50 |
| Licence | Proprietary | Proprietary |
| Max output | — | 128K |
| Parameters | — | Not published |
| Released | — | 1 Sep 2026 |
| Model ID | — | claude-fable-5-1 |
| Category | Language Models | Language Models |
| Official | OpenAI ↗ | — |
Highlighted rows are where these differ.
Claude Fable 5.1
- Matches or beats Fable 5 at low and medium effort, and pulls clear at high effort
- Cache reads cut to 25% of the old price, so re-reading a long context got much cheaper
- Identical model to Mythos 5.1 underneath; the difference is the safeguards
Best for coding and long-running work.