OpenAI splits ChatGPT tiers between GPT-5.6 Sol and Luna
Paid ChatGPT users get an updated GPT-5.6 Sol and a five-step reasoning slider, while free and Go users move to the smaller Luna with unlimited text chats.
OpenAI restructured how ChatGPT's roughly billion-user base reaches its models on Wednesday, publishing a product note that redraws the line between paid and free access rather than launching a new frontier system.
What changed for paid users
Plus and Pro subscribers now run every conversation on a revised build of GPT-5.6 Sol, including the fast "Instant" path that previously used a separate lighter model. OpenAI says the updated Sol trims padding and heavy formatting in favour of shorter answers that lead with a recommendation. Alongside it, paying users get a slider offering five levels of reasoning effort, letting them trade latency against depth per query instead of picking a model from a dropdown. On the company's internal high-stakes factuality evaluation, it reports factual errors falling about 68 percent for Sol relative to the older GPT-5.5 Instant configuration; the figure has not been independently reproduced.
What changed for free users
Free and Go accounts move to GPT-5.6 Luna, a smaller model, as their default. They also gain a "Think" button that lets Luna reason for longer on harder prompts — but it extends the small model's thinking rather than escalating to Sol. OpenAI reports a roughly 62 percent drop in factual errors for Luna against the same baseline. The sweetener is capacity: unlimited text conversations, arriving next week, ending the message caps that have defined the free tier since launch. Separate quotas still apply to files, images, voice and image generation. Sol-tier changes shipped immediately; the free-tier changes roll out across this week and next.
Why it matters
This is the clearest statement yet of how OpenAI intends to make consumer inference pay. Unlimited text at the bottom of the funnel is cheap only if the bottom of the funnel is served by a small model, and the Think button is designed to absorb demand for reasoning without routing it to expensive weights. The structural consequence is a widening quality gap between free and paid ChatGPT that is now explicit rather than incidental — a template rivals distributing free assistants at scale will have to answer, and a change in what hundreds of millions of people actually get when they ask an AI a hard question.