ChatGPT free users upgraded to GPT-5.6 Luna with unlimited text chat

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TL;DR

OpenAI’s latest ChatGPT update brings meaningful upgrades to the GPT-5.6 lineup.

The top-tier GPT-5.6 Sol model will now make fewer factual errors, limit unnecessary information, and can adapt its reasoning based on your query.

Free users are moving from GPT-5.5 Instant to GPT-5.6 Luna with unlimited text chats and a new Think button for deeper reasoning.

ChatGPT’s latest 5.6 model lineup made its official debut early in July. Less than a month later, the AI giant is already giving the state-of-the-art models a brain and accessibility boost.

As you may recall, the 5.6 series consists of three models: Sol, Terra, and Luna. There’s no update to Terra, but GPT-5.6 Sol and GPT-5.6 Luna are getting meaningful upgrades . These range from making the models more reliable, accurate, and focused, to expanding access for users who don’t want to pay for top-tier AI.