Positioning and release
GPT-6 Luna (October 29) is an update to the GPT-6 Luna model released in ChatGPT on October 7, 2026. OpenAI published the update’s system-card addendum on October 29, 2026. The update is intended to produce more concise responses and use less overly agreeable language. Although the supplied source URL contains “october-28,” the page itself states October 29. (deploymentsafety.openai.com)
OpenAI positions GPT-6 Luna as an efficient model for focused, high-volume tasks. The October 29 addendum does not establish a separate API identifier for that dated update. (developers.openai.com)
Capabilities and uses
- The GPT-6 Luna API model supports text input and output and image input. It supports adjustable reasoning effort, function calling and structured outputs; the Responses API also supports built-in tools. Potential uses include coding, professional work and high-volume application workflows. (developers.openai.com)
- The API model documentation lists a 1,050,000-token context window, a 128,000-token maximum output and a May 18, 2026 knowledge cutoff. These specifications are for GPT-6 Luna generally, not separately verified for the October 29 ChatGPT update. (developers.openai.com)
- OpenAI reports improved under-18 safety evaluation results for sexual content, eating disorders, emotional reliance and gore compared with the October 7 version. It also reports 99.91% robustness on its instruction-hierarchy evaluation; that result does not guarantee immunity to prompt injection. (deploymentsafety.openai.com)
Limitations and safety
The documented API model does not support audio or video input, and does not support fine-tuning. Its responses can still be incorrect, and benchmark scores do not guarantee real-world performance. In the addendum, OpenAI treats the October 29 update as High capability in both cybersecurity and biological and chemical domains and says it uses the same safeguards stack as the October 7 version. (developers.openai.com)
Pricing
OpenAI’s published GPT-6 Luna API text-token prices below are in USD per 1 million tokens, checked November 15, 2026. They are general model pricing, not a separately confirmed price for the October 29 ChatGPT update. (developers.openai.com)
| Standard processing | Input | Cached input | Cache writes | Output |
|---|---|---|---|---|
| Up to 272,000 input tokens | $0.10 | $0.01 | $0.125 | $0.50 |
| More than 272,000 input tokens | $0.20 | $0.02 | $0.25 | $0.75 |
For prompts over 272,000 input tokens, the long-context rates apply to the entire request. Batch and Flex are priced at 50% of Standard rates; Fast mode is priced at twice the applicable rates. Regional processing adds 10% where available. Tool usage may incur separate fees. (developers.openai.com)