In ChatGPT, GPT-6 Is Sol and GPT-6 Pro Is Astra

OpenAI brought GPT-6 to ChatGPT's Chat tab on Oct 7, 2026, and which GPT-6 model answers depends on the plan. The model menu doesn't name it. OpenAI's help center tells users to look for GPT-6 in the menu, which "is not labeled Sol", and says its Pro level runs GPT-6 Pro, powered by GPT-6 Astra.

Sol behind GPT-6, Astra behind Pro

In the model menu, GPT-6 replaces Latest, and a Thinking slider sets the effort. "When GPT-6 is selected, GPT-6 Sol powers Instant, Medium, High, and Extra High; Pro uses GPT-6 Pro, powered by GPT-6 Astra," the help center says. On paid plans GPT-5.6 Sol stays a separate choice in the menu, its Pro level running GPT-5.6 Sol Pro, and "The GPT-6 rollout does not retire older selectable models." The Oct 7 post says the Chat models are "tuned for everyday conversation". The rollout began that day for Plus, Pro, Business and Enterprise, with Enterprise availability depending on admin settings.

Pro, Business and Enterprise get Astra

The help center's table of thinking levels gives Pro, Business and Enterprise every level, Extra High and Pro included. It lists GPT-6 Pro for "Pro $100, Pro $200, Business, and Enterprise plans", and OpenAI's page on the Pro tiers says "Pro 100 and Pro 500 keep their current weekly GPT-6 Pro message limits in Chat." Business Standard seats include 15 Pro messages a month and Premium seats 50 a week, shared with GPT-5.6 Sol Pro. In Enterprise workspaces, "GPT-6 Astra is off by default at launch" until an owner turns it on.

Plus stops at High

Plus gets GPT-6 Sol at Medium and High in the help center's table, and not Extra High or Pro. "Plus includes Astra in Work and Codex, but not GPT-6 Pro in Chat," OpenAI's guide to Astra usage says.

Free and Go get GPT-6 Luna

The Oct 7 post says GPT-6 in ChatGPT is powered "by GPT‑6 Sol for Plus, Pro, Business, and Enterprise tiers, and GPT‑6 Luna for Free and Go tiers", with the Free and Go rollout starting the next day. The help center's table of thinking levels includes none of Medium, High, Extra High or Pro for Free and Go. The same page says "Free and Go users can use Think for harder questions."

Work and Codex have their own models

Work and Codex have their own model picker, and OpenAI's release notes said on Sep 22 that the GPT-6 Sol and Luna there "are separate from the models available in Chat." GPT-6 Sol and Luna reached Work and Codex on Sep 22 for Plus, Pro, Business, Enterprise and Edu, and "Free and Go users can access GPT‑6 Luna in the desktop app." GPT-6.1 Sol followed there on Sep 29. The Astra guide says Plus includes Astra in Work and Codex. The GPT-6 family tree dates every GPT-6 model and its price.