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OpenAI expands GPT-5.6 Luna to free ChatGPT text chats

OpenAI announced an August 6 ChatGPT update that changes the model experience for both free and paid users. Free and Go users are moving to GPT-5.6 Luna as the default model this week, with unlimited text chats and a new Think button scheduled for next week, while Plus and Pro users get an updated GPT-5.6 Sol with a slider for choosing how much reasoning effort ChatGPT applies.

The important boundary is just as clear: OpenAI says this release applies to the everyday ChatGPT chat experience. ChatGPT Work and Codex continue using their previously released GPT-5.6 Sol and Luna versions, so developers should not assume coding-agent behavior, pricing, or model baselines changed at the same time.

Key takeaways

• Free and Go users are scheduled to get GPT-5.6 Luna as the default model this week.
• Unlimited text chats and a new Think button for harder questions are slated for next week, subject to abuse guardrails.
• Plus and Pro users can use an updated GPT-5.6 Sol and a reasoning-effort slider on web, mobile, and desktop.
• File uploads, images, and other non-text tools still have limits.
• ChatGPT Work and Codex are explicitly outside this August Chat release.

Free ChatGPT moves to GPT-5.6 Luna

OpenAI frames the free-tier change as a broader access move rather than a full unlock of its flagship model. GPT-5.6 Luna becomes the default everyday model for Free and Go users, and the coming unlimited-text window removes the ordinary text-chat cap for those users.

That does not mean every ChatGPT surface becomes unlimited. OpenAI says limits remain for file uploads, image features, and other tools. The new Think button gives GPT-5.6 Luna more time for harder questions, but the company has not described it as free access to GPT-5.6 Sol.

Paid users get one Sol experience with a slider

For Plus and Pro users, OpenAI says the updated GPT-5.6 Sol now powers both quick replies and deeper reasoning in ChatGPT. The product change is a shift away from a sharper split between instant answers and thinking-style responses. A new slider lets users choose how much thought ChatGPT puts into an answer.

OpenAI says the retuned Sol is designed to be more focused, use tighter formatting, and make fewer factual mistakes, especially when answers depend on dates, numbers, rules, sources, or assumptions. In an internal evaluation covering financial, medical, and legal prompts, OpenAI reports that responses with at least one factual error were about 68% less common with the updated GPT-5.6 Sol than with GPT-5.5 Instant. Treat that as a vendor-reported benchmark, not an independent audit.

Work and Codex stay on the July models

The release has a practical scope line for teams that use ChatGPT as an operator surface. OpenAI says the August GPT-5.6 Sol is optimized for everyday ChatGPT chat and is not replacing the GPT-5.6 versions used in ChatGPT Work or Codex.

That matters for saved workflows, coding agents, workspace defaults, evals, and admin documentation. A user may feel a changed Sol behavior in consumer ChatGPT while their Codex session or Work deployment remains pinned to the prior July model version. Teams should label screenshots, model comparisons, and support notes by product surface and date.

Safety notes accompany broader access

OpenAI also published a GPT-5.6 August Updates system card. It says the August Sol and Luna releases are treated as High capability in Cybersecurity and Biological and Chemical domains under OpenAI's Preparedness Framework, while not reaching the High threshold in AI Self-Improvement.

The same document says OpenAI added dedicated under-18 evaluations and additional safeguards for teen-specific risks, including romantic roleplay, age-restricted content, eating disorders and body-image issues, dangerous activities, and situations where a user may need trusted real-world support. These are OpenAI's stated safeguards and internal evaluations; real-world behavior still needs external scrutiny as access expands.

The immediate operator takeaway is simple: free ChatGPT text volume is expanding on Luna, paid Chat gets a more unified Sol control surface, and serious work surfaces did not automatically inherit the August retune.

Source check

• OpenAI's primary announcement confirms the August 6 ChatGPT update, Free and Go Luna rollout, Plus and Pro Sol slider, and Work/Codex scope boundary.
• ChatGPT release notes corroborate the rollout timing and remaining limits for files, images, and other tools.
• GPT-5.6 August Updates system card provides safety and capability context for the August Sol and Luna models.
• TechCrunch coverage independently reports the free-user unlimited text-chat expansion.