Explainer
GPT-6.1 Sol, GPT-6 Astra, Sol and Luna: which model you get in ChatGPT, and what’s free
OpenAI released a lot of models in a few weeks, with confusing names. Here’s which ones exist, which ChatGPT plan gets which, what changed on October 7, and why you can’t use “GPT-6.1 Astra” however many search results promise it.
GPT-6.1 Sol launched September 29, 2026, but only in ChatGPT Work, Codex and the API, for Plus and higher, not in regular chat. On October 7, regular chat got GPT-6: GPT-6 Sol for paid plans and GPT-6 Luna for Free and Go, plus interactive “Intelligent UI” answers. GPT-6.1 Astra doesn’t exist for users: its release was reportedly cancelled.
The current GPT-6 models in plain words
| Model | What it’s for | Released |
|---|---|---|
| GPT-6 Astra | OpenAI’s most capable model; powers “Pro” reasoning | Sept 3, 2026 |
| GPT-6 Sol | The everyday model for paid plans in chat | Sept 22, 2026 |
| GPT-6 Luna | Fast and efficient; the model for Free and Go | Sept 22, 2026 |
| GPT-6.1 Sol | An upgrade to Sol for coding, computer use and long tasks, “near-Astra” at lower cost | Sept 29, 2026 |
Which ChatGPT plan gets which model
| Model | Free | Go | Plus | Pro |
|---|---|---|---|---|
| GPT-6 Luna | Yes | Yes | Yes | Expanded |
| GPT-6 Sol | No | No | Yes | Expanded |
| GPT-6.1 Sol (Work and Codex) | No | No | Yes | Expanded |
| GPT-6 Astra | No | No | Yes (limited) | Expanded |
| Older GPT-5.6 models | No | No | Yes | Yes |
From ChatGPT’s pricing page grid and OpenAI’s announcements, checked Oct 12, 2026.
So the real dividing line is Free/Go versus Plus: Free and Go get GPT-6 Luna, and Plus is the first plan with Sol, 6.1 Sol and Astra. Full plan comparison: Free vs Go vs Plus.
What changed on October 7: GPT-6 in regular chat
- The regular Chat tab moved to GPT-6: GPT-6 Sol for Plus, Pro, Business and Enterprise from October 7, and GPT-6 Luna for Free and Go from October 8.
- Intelligent UI: answers can now include graphics, tappable buttons, forms, charts and small interactive tools, such as a bill splitter or retirement calculator, inside the chat.
- GPT-6 can start answering while it’s still thinking or using tools, then add findings without another prompt.
- The models in ChatGPT Work and Codex didn’t change with this update, and the Pro reasoning option (GPT-6 Astra) doesn’t use Intelligent UI.
GPT-6.1 Sol: what’s new
OpenAI calls GPT-6.1 Sol “near-Astra intelligence for a fifth of the price”: an upgrade to GPT-6 Sol that nearly matches GPT-6 Astra on coding, computer use and professional work. OpenAI also reports about a third fewer factual errors than GPT-6 Sol on hard prompts. These are OpenAI’s own tests, run in its research environment.
- Where: ChatGPT Work and Codex for Plus, Pro, Business, Enterprise and Edu. OpenAI says it’s “not yet available in Chat”.
- For developers: in the API as
gpt-6.1-sol, at $2 per million input tokens and $10 per million output tokens. - Ultrafast: a much faster speed mode on the Pro 500 plan; see Pro 100 vs 200 vs 500.
New to Work? ChatGPT Work vs regular chat explains it.
What happened to GPT-6.1 Astra?
Lots of people search for “GPT-6.1 Astra free”, but there’s nothing to use. According to The Wall Street Journal, confirmed by OpenAI to Reuters, OpenAI cancelled the planned October release of GPT-6.1 Astra after internal safety testing found it didn’t stay within scope and authorization well enough reported. No OpenAI product page lists it. The most capable model you can use is GPT-6 Astra, available with limits on Plus and expanded on Pro. Sites offering “free GPT-6.1 Astra” are selling something else.
Which model should you pick?
- On Free or Go: you get GPT-6 Luna automatically; nothing to choose. It’s good for everyday questions and writing. Know its free plan limits.
- On Plus: leave chat on its default (GPT-6 Sol); use Work or Codex for long jobs, where GPT-6.1 Sol is available; pick Astra only for hard reasoning, since it’s limited.
- Accuracy matters? Any model can still be confidently wrong; these 7 prompts make it check its work.
Sources: OpenAI: introducing GPT-6.1 Sol · OpenAI: GPT-6 and Intelligent UI for everyone (Oct 7, 2026) · OpenAI: DevDay 2026 recap · OpenAI: ChatGPT release notes · ChatGPT pricing · TechCrunch: GPT-6.1 Sol launch · Al Jazeera: OpenAI scraps GPT-6.1 Astra release
Quick answers
Is GPT-6.1 free?
No. GPT-6.1 Sol is available to Plus, Pro, Business, Enterprise and Edu users in ChatGPT Work and Codex, and to developers through the API. It isn’t in regular ChatGPT chat yet, and Free and Go users don’t get it.
Is GPT-6.1 Astra free?
There is no GPT-6.1 Astra to use. OpenAI reportedly cancelled its planned October release after safety testing. The top model you can use is GPT-6 Astra, on Plus (limited) and Pro.
When was GPT-6.1 released?
GPT-6.1 Sol was announced on September 29, 2026 at OpenAI’s DevDay. The October 7 update was something else: GPT-6 Sol and GPT-6 Luna arriving in the regular Chat tab with Intelligent UI.
What model does free ChatGPT use?
GPT-6 Luna, since October 8, 2026. Some older OpenAI help pages still say GPT-5.6 Luna; the pricing page and the October 7 announcement say GPT-6 Luna.
What is Intelligent UI in ChatGPT?
A GPT-6 feature that lets answers include visuals and interactive pieces, such as side-by-side comparisons, diagrams, charts and small tools like calculators or bill splitters, right in the chat. It rolled out to all plans from October 7, 2026.
Keep learning
ChatGPT Free vs Go vs Plus: which plan is worth paying for?
ChatGPT Free, Go ($8) and Plus ($20) compared from OpenAI’s own pricing page: models, limits, ads, deep research and Codex, and who should pick which.
ChatGPT free plan limits in 2026: messages, uploads, images, and how to turn off ads
Free ChatGPT gives unlimited everyday chats with GPT-6 Luna, 3 file uploads a day, limited images and deep research, and may show ads. Exact limits and resets.
ChatGPT Pro 100 vs Pro 200 vs Pro 500: what the extra money buys
ChatGPT Pro now costs $100, $200 or $500 a month. What differs (usage, Ultrafast, voice), the Oct 29 Pro 200 change, and who needs which tier, from OpenAI’s pages.