GPT-5.6 Luna Pro is the same underlying model as [GPT-5.6 Luna](https://openrouter.ai/openai/gpt-5.6-luna), served with `reasoning.mode` set to `pro` for higher-quality responses on complex tasks. Learn more in OpenAI's docs: https://devel…
Model details →OpenAI: GPT-5.6 Luna Pro vs Anthropic: Claude Fable Latest
OpenAI: GPT-5.6 Luna Pro wins on 3 of 6 axes — pricing and capability skew in its favour for most workloads.
This model always redirects to the latest model in the Claude Fable family.
Model details →Side-by-side comparison
| Capability | OpenAI: GPT-5.6 Luna Pro | Anthropic: Claude Fable Latest | Winner |
|---|---|---|---|
| Context window Maximum number of input tokens the model can attend to in a single request. | 1.1M | 1M | 🏆 OpenAI: GPT-5.6 Luna Pro |
| Input price (per 1M) Cost per million input tokens billed by the provider. | $0.10 | $10.00 | 🏆 OpenAI: GPT-5.6 Luna Pro |
| Output price (per 1M) Cost per million output tokens billed by the provider. | $0.60 | $50.00 | 🏆 OpenAI: GPT-5.6 Luna Pro |
| Tool / function calling First-class support for emitting structured tool calls. | Yes | Yes | Tie |
| Vision input Accepts image inputs alongside text. | Yes | Yes | Tie |
| Reasoning mode Internal chain-of-thought / extended-thinking support. | Yes | Yes | Tie |
Frequently asked questions
Is OpenAI: GPT-5.6 Luna Pro better than Anthropic: Claude Fable Latest?
OpenAI: GPT-5.6 Luna Pro wins on 3 of 6 axes — pricing and capability skew in its favour for most workloads.
What's the price difference between OpenAI: GPT-5.6 Luna Pro and Anthropic: Claude Fable Latest?
Input: $0.10 vs $10.00 per 1M tokens. Output: $0.60 vs $50.00 per 1M tokens.
What context windows do OpenAI: GPT-5.6 Luna Pro and Anthropic: Claude Fable Latest support?
OpenAI: GPT-5.6 Luna Pro supports up to 1.1M tokens. Anthropic: Claude Fable Latest supports up to 1M tokens.
Do both OpenAI: GPT-5.6 Luna Pro and Anthropic: Claude Fable Latest support tool calling?
OpenAI: GPT-5.6 Luna Pro: yes. Anthropic: Claude Fable Latest: yes.
Compare OpenAI: GPT-5.6 Luna Pro with other models
vs Anthropic Claude Haiku Latestvs Anthropic Claude Sonnet Latestvs Anthropic: Claude Fable Latestvs Anthropic: Claude Opus Latest