OpenAI is removing limits on text-based chats for all ChatGPT users, including Free and Go tiers, powered by a new GPT-5.6 Luna model that replaces GPT-5.5. Free and Go users also gain a new 'Think' button for higher reasoning on complex queries. Plus and Pro users get an upgraded GPT-5.6 Sol model with more compact and robust answers, plus a thinking slider to control reasoning depth. Internal evaluations show GPT-5.6 Luna reduces factual errors by 62% and GPT-5.6 Sol by 68% compared to GPT-5.5-Instant. Unlimited text chats and the Think button roll out next week; the upgraded Sol model is available to Plus and Pro users immediately.
Questions this post answers
What is the default model for ChatGPT Free and Go users after the GPT-5.6 update?
GPT-5.6 Luna is the new default model for ChatGPT Free and Go users, replacing GPT-5.5. It powers unlimited text-based chats and includes a new 'Think' button for higher reasoning on complex queries. Compared to GPT-5.5-Instant, GPT-5.6 Luna produces 62% fewer factual errors. Separate limits still apply for files, images, voice, and image generation. Developers relying on ChatGPT Free for daily tasks can track model changes like this on daily.dev.
How does GPT-5.6 Sol differ from GPT-5.6 Luna in ChatGPT?
GPT-5.6 Sol is the upgraded model for ChatGPT Plus and Pro users, optimized for quick tasks like web research, writing, and decision-making with more compact and robust answers. GPT-5.6 Luna is the default for Free and Go users. Sol reduces factual errors by 68% vs GPT-5.5-Instant, compared to 62% for Luna. The Sol version used for Codex and Work is a separate, unchanged variant. Teams choosing between ChatGPT tiers for their workflows can follow OpenAI model updates on daily.dev.