OpenAI gives free users unlimited GPT-5.6 Luna text chat, rolling out next week
On August 7, OpenAI upgraded free and Go subscribers' default model to GPT-5.6 Luna, removed text chat limits, and added a Think button for complex questions. Plus and Pro users get a tuned GPT-5.6 Sol for chat plus a reasoning slider.
On August 7, OpenAI announced a major ChatGPT update, switching the default model for free and Go subscribers from GPT-5.5 Instant to GPT-5.6 Luna and removing text chat limits starting next week. File uploads, image generation, and voice chat remain on separate quotas.
GPT-5.6 Luna is the fastest and cheapest tier of the GPT-5.6 family. On July 30, OpenAI cut Luna's API price by 80%, to $0.20 per million input tokens and $1.20 per million output tokens. In internal evals on finance, medical, and legal prompts requiring concrete facts, Luna produced at least one factual error in roughly 62% fewer responses than GPT-5.5 Instant.
For Plus and Pro subscribers, OpenAI tuned the chat version of GPT-5.6 Sol to be more direct, reduce format overhead, and push back when the user is wrong. Internal evals show Sol produced at least one factual error in about 68% fewer responses than GPT-5.5 Instant. The optimization only affects ChatGPT's chat surface; the Sol versions used in Work and Codex are unchanged.
Paid users also get a 5-step reasoning slider to dial thinking depth up or down by task complexity. OpenAI disclosed ChatGPT now has 1 billion weekly active users.