The GPT-5.6 Sol update arrives as free users gain GPT-5.6 Luna, unlimited text chats and a new Think button.
OpenAI has updated the version of GPT-5.6 Sol used in ChatGPT, aiming to provide more focused and factually reliable answers across quick conversations and complex reasoning tasks.
For Plus and Pro users, the same model now powers both Instant responses and higher-effort reasoning. OpenAI says GPT-5.6 Sol adjusts its level of detail to the question, uses less unnecessary formatting and offers corrections when simply agreeing would be unhelpful.
A new reasoning slider is available across ChatGPT on web, mobile and desktop. Users can prioritise speed for everyday questions or allocate more reasoning to planning, research, writing, coding and complex decisions.
Factual reliability is another focus. In an internal OpenAI evaluation covering financial, medical and legal prompts requiring detailed facts, responses containing at least one factual error were 68% less common with GPT-5.6 Sol than with GPT-5.5 Instant. GPT-5.6 Luna reduced such responses by 62%.
OpenAI is also expanding access for Free and Go users. GPT-5.6 Luna is due to become their default model during the week of the announcement. Unlimited text conversations and a Think button for higher-effort responses are expected the following week, subject to safeguards against abuse.
Limits will continue to apply to file uploads, images and other tools. The updated version of GPT-5.6 Sol is designed specifically for everyday ChatGPT conversations, while the versions used in Work and Codex remain unchanged.
Additional protections apply to users OpenAI believes are under 18. The company says the model has stronger boundaries covering romantic roleplay, sexual material, eating disorders, dangerous activities and other age-sensitive content, while encouraging young users to seek support from trusted people where appropriate.
Why does it matter?
Using a single model for both quick and in-depth responses could make ChatGPT more consistent while giving users clearer control over speed and reasoning. Wider free access may also reduce barriers to advanced AI, although OpenAI’s reliability improvements and youth safeguards still require independent assessment.
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