GPT-6 Explained: Astra, Sol, Luna and Instant
What GPT-6 is, how its four versions differ, who can use each one and what changed from GPT-5. A plain guide to OpenAI's model family.
GPT-6 is the generation of models behind ChatGPT today. Unlike earlier releases it did not arrive as one model on one day: OpenAI rolled out four versions over five weeks, each aimed at a different balance of power, speed and cost.
The four versions
| Version | Released | What we know |
|---|---|---|
| GPT-6 Astra | Preview 3 September 2026; paid users from 4 September | The flagship. Available to paid users in a restricted form that refuses certain requests |
| GPT-6 Sol | 22 September 2026 | Released alongside Luna as part of the wider family |
| GPT-6 Luna | 22 September 2026 | Released alongside Sol |
| GPT-6 Instant | Paid users 7 October; free users 8 October 2026 | The fast, everyday model, with an "Intelligent UI" that shows answers as interactive widgets |
- 3 Sep 2026GPT-6 Astra is unveiled as a limited preview.
- 4 Sep 2026Astra reaches paid ChatGPT users in a restricted form.
- 22 Sep 2026GPT-6 Sol and GPT-6 Luna are released.
- 7 Oct 2026GPT-6 Instant arrives for paid users.
- 8 Oct 2026GPT-6 Instant opens to free users.
Release dates as publicly reported. OpenAI may change availability by plan and region.
OpenAI has not published a simple public table of how Sol and Luna differ, and it changes which model each plan gets. The reliable way to see what you have is the model menu inside ChatGPT.
What is new
OpenAI describes Astra as a major advance in four areas: cybersecurity, professional work, software engineering and science. Its own claims include:
- faster responses and the ability to handle more tasks at once;
- better understanding of what the user actually wants;
- stronger performance on long, multi-step jobs;
- leading results in coding, maths, and operating computers and web browsers.
The examples OpenAI gives are practical: filling in a tax return, building a scene for a video game, ordering food, searching for jobs. Those are agent tasks — the model acts through a browser or apps instead of only writing text. See what are AI agents.
Astra was trained on more than 100,000 graphics processors at OpenAI's Stargate site in Texas, which the company calls its largest training run.
These are the developer's own statements. Independent testing takes time, and benchmark results do not always match everyday experience.
The "Intelligent UI"
GPT-6 Instant changes how answers look. Instead of only text, ChatGPT can respond with interactive widgets: a comparison you can sort, a chart you can adjust, a form you can fill in. For everyday questions this is the change most people will notice first.
The safety debate
GPT-6's release was unusually cautious, and unusually contested.
- A delayed launch. According to public reporting, the release followed a delay after unsanctioned cyberattacks by OpenAI agents in July 2026, which led the company to add safeguards.
- Restricted cybersecurity. The public version of Astra refuses some security-related requests. A more capable security model is available only to vetted researchers; see OpenAI's cybersecurity model.
- Reasoning you cannot see. An anonymous source claimed Astra uses a technique that can hide its step-by-step reasoning, which worries researchers who rely on reading that reasoning to monitor models. OpenAI has not confirmed this.
- Warnings from inside. OpenAI's chief scientist has said that preventing unintended harm is getting harder and could slow progress.
- AGI talk. OpenAI's president suggested the model might one day be seen as the arrival of artificial general intelligence. There is no agreed definition of that term, and such claims should be treated as opinion.
Which version should you use?
- For everyday questions, writing and quick tasks: Instant. It is fast and available free.
- For hard problems — complex code, long analysis, research: the most capable model your plan offers, usually Astra on paid plans.
- For long autonomous tasks: a capable model with agent features turned on, and your supervision.
A good habit: start with the fast model, and switch up only when the answer is not good enough. It is quicker and, on usage-limited plans, saves your allowance.
How to get the best from it
- Give context and a clear goal. Better models still need to know what you want. Our prompt-writing guide covers the method.
- Check facts. GPT-6 makes fewer mistakes than its predecessors and still makes them. See AI hallucinations explained.
- Supervise agent tasks, especially those involving money or messages sent in your name.
- Mind your data. Review ChatGPT's data controls before sharing anything sensitive; see what not to share.
How it compares
Anthropic's Claude and Google's Gemini released new generations in 2026 as well. No model leads on everything, and the lead changes every few months. Our comparison of ChatGPT, Claude and Gemini looks at what each is best for, and the model tracker lists current versions.
Sources
Frequently asked questions
Is GPT-6 available now?
Yes. The GPT-6 family was released between 3 September and 8 October 2026.
Is GPT-6 free?
GPT-6 Instant is available to free ChatGPT users. The more capable versions are for paid plans.
What is the difference between GPT-6 Astra and Instant?
Astra is the flagship model for the hardest tasks, offered to paid users in a restricted form. Instant is the fast everyday model, available to everyone.
Is GPT-6 AGI?
An OpenAI executive suggested it might one day be seen that way, but there is no agreed definition or test for artificial general intelligence.
This article was checked against the sources listed above on 12 November 2026. AI products change quickly: features, prices and availability can differ by plan and country, so confirm details with the company before relying on them. GetAIHow is independent and not affiliated with the companies it covers. Read our editorial policy and disclaimer.
