OpenAI improves GPT-5.6 Sol in ChatGPT and restricts free users to its weakest model
Update –
OpenAI reached out after publication to clarify that GPT-5.6 Luna, while the smallest model in the GPT-5.6 family, is still a step up from the previous free default, GPT-5.5 Instant. The company says it's "not accurate to represent this as free users being restricted to a weaker experience," adding that their capabilities have only grown compared to what was available before. The text was updated to reflect that better.
OpenAI's remark is true, but my core point stands. The free tier has improved in absolute terms, but free users no longer get any access to OpenAI's frontier reasoning models. This isn't new, but it wasn't always the case. In our own testing, the quality gap is hard to miss. Many people don't realize this because they assume "ChatGPT is ChatGPT." It's not, and this isn't a knock on OpenAI so much as a heads-up that there's a real quality difference between tiers.
OpenAI is giving Plus and Pro users a more focused GPT-5.6 Sol and a slider for adjusting response depth. Free users will get unlimited text chats with the cheaper GPT-5.6 Luna.
OpenAI says GPT-5.6 Sol now cuts unnecessary detail and excess formatting. For simple questions, it delivers a direct answer with just enough context, while more complex tasks get a fuller response that still makes the key recommendation easy to spot.
The company also claims better factual accuracy. In an internal evaluation using finance, medicine, and law prompts, responses with at least one factual error fell about 62 percent for GPT-5.6 Luna and 68 percent for GPT-5.6 Sol compared with GPT-5.5 Instant. Those figures haven't been independently verified.
The update only applies to ChatGPT. GPT-5.6 Sol remains unchanged in ChatGPT Work and Codex.
Paying users get more control over reasoning
A new slider lets paying users adjust how much effort ChatGPT puts into a response. Lower settings suit everyday questions, while higher settings are meant for planning, research, and coding. The slider was already available in ChatGPT Work.
OpenAI says it wants quick answers and deeper reasoning to feel like one model rather than two with different tones. An OpenAI developer recently broke down which of the five settings fits which type of task. The slider works on web, mobile, and desktop.
It's worth asking whether these controls actually help people use AI better, though. Users largely ignored the model switcher, and picking the right model for a task likely mattered way more than choosing among five reasoning levels. Adding more knobs to turn doesn't make the experience better.
Free users get more chats but a weaker model
GPT-5.6 Luna will become the default for Free and Go users later this week, according to OpenAI's release notes. Unlimited text chats and a new "Think" button for harder questions will follow next week, though limits on file uploads, image generation, and other tools will stay in place.
Luna may perform well for its size, but smaller models are generally more error-prone and less reliable. A case involving the previous Instant model, which produced a completely wrong data analysis compared to its larger reasoning counterpart, made that risk clear. Since the Think button only lets Luna reason longer rather than switching to a stronger model, free users still don't get access to OpenAI's frontier reasoning. That wasn't always the case.
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