Pyyan / Compare / GPT-6 Luna vs Claude Fable 5.1
GPT-6 Luna vs Claude Fable 5.1
2 of 5Language Models · verified 24 Sept 2026
GPT-6 LunaOpenAIcurrentClaude Fable 5.1Anthropiccurrent
| Specification | GPT-6 Luna | Claude Fable 5.1 |
|---|---|---|
| Summary | Ten cents a million in, for the work that does not need thinking. | Same price as Fable 5, and cache reads cost a quarter of what they did. |
| Context | 1.05M | 1M |
| Input ($/Mtok) | $0.1 | $10 |
| Output ($/Mtok) | $0.5 | $50 |
| Licence | Proprietary | Proprietary |
| Max output | 128K | 128K |
| Parameters | Not published | Not published |
| Released | 22 Sep 2026 | 1 Sep 2026 |
| Model ID | gpt-6-luna | claude-fable-5-1 |
| Category | Language Models | Language Models |
| Official | OpenAI ↗ | — |
Highlighted rows are where these differ.
GPT-6 Luna
- Half the price of GPT-5.6 Luna, which it replaces at the bottom of the family
- Beats or matches GPT-5.6 Luna on all five benchmarks OpenAI published
- Same 1.05M context window as the tiers above it
Best for classification and high-volume chat.
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.