OpenAI Brings GPT-5.6 to More Users With Smarter Sol, Free Unlimited Luna Chats

OpenAI is expanding access to its GPT-5.6 model family across ChatGPT, introducing a simplified experience that gives free users unlimited conversations with its lightweight Luna model while upgrading paid subscribers to the more capable Sol model for both everyday chats and advanced reasoning.

The rollout is happening globally over the next 24 hours.

GPT-5.6, first introduced in preview earlier this year, includes three models: Sol for frontier reasoning, Terra as a balanced option, and Luna as the fastest and most cost-efficient variant.

Interestingly, last month, after the rollout of GPT 5.6 Sol, several users claimed it deleted files, databases, and other data without explicit permission.

Under the update, Free and Go users will receive unlimited text chats powered by GPT-5.6 Luna, including a "Think" option that allocates additional reasoning time for more complex queries. However, image generation, file uploads and other premium tools will continue to have usage limits.

"OpenAI is working hard to empower everyone with intelligence that works for them, in the form of great products which get simpler to use over time. We're bringing unlimited text chats with Luna, a quite capable model, to free users," Greg Brockman, OpenAI President & Co-Founder, said.

For Plus and Pro subscribers, OpenAI has streamlined the experience by making GPT-5.6 Sol the default model for both fast responses and deeper reasoning.

Instead of switching between separate models, paid users can now adjust a reasoning slider to control how much computation the model uses based on the complexity of the task.

The company said the updated Sol model produces more focused answers, is more willing to challenge incorrect assumptions, and reduces unnecessary formatting.

In OpenAI's internal evaluations across finance, medicine and legal tasks, GPT-5.6 Sol reduced responses containing at least one factual error by 68% compared with GPT-5.5 Instant, while GPT-5.6 Luna reduced such errors by 62%.

It is important to note here that the results are based on OpenAI's own testing and have not yet been independently validated.