OpenAI launches GPT-5.6 Luna as default for free ChatGPT users with unlimited text chats

OpenAI is making GPT-5.6 Luna the default model for Free and Go ChatGPT users, replacing GPT-5.5 Instant. Starting this week, both plans will get unlimited text chats without rate limits, although limits will remain for file uploads, images, and other ChatGPT tools. A new Think button is also coming next week, giving Free and Go users access to higher reasoning when needed.

Plus and Pro users are getting an updated GPT-5.6 Sol with improved factual reliability, particularly for answers involving dates, numbers, sources, rules, and assumptions. OpenAI says the model should also give more focused responses, avoid unnecessary detail and formatting, and correct users when simply agreeing would not be useful. Plus and Pro subscribers can also use a new reasoning slider to control how much thought ChatGPT puts into a response.

OpenAI has also made the tone and behavior of Instant and Thinking more consistent. The updated GPT-5.6 Sol and reasoning slider are available now in ChatGPT, including the iPhone, iPad, and Mac apps. These changes apply only to ChatGPT and don't affect GPT-5.6 Sol in Work or Codex.