OpenAI updating ChatGPT with a smarter GPT-5.6 Sol and unlimited free chats

OpenAI announced an update to ChatGPT that introduces a revised GPT-5.6 Sol model for paying subscribers and unlimited text chats for free users. The company said the updated model produces more focused answers, adapts detail levels to each question, and avoids unnecessary formatting. OpenAI also said the revised model is more reliable when answering questions involving dates, numbers, rules, sources, and assumptions. In an internal evaluation covering financial, medical, and legal prompts, answers containing at least one factual error were reportedly 68% less common with GPT-5.6 Sol than with GPT-5.5 Instant. The update unifies ChatGPT's Instant and Thinking experiences for Plus and Pro subscribers. Both tiers will use GPT-5.6 Sol with a new slider controlling how much thought the model puts into its response. The slider will be available across web, mobile, and desktop apps. Free users receive unlimited text chats using GPT-5.6 Luna and a new Think button for harder questions requiring deeper reasoning. OpenAI said the GPT-5.6 Sol version powering ChatGPT Work and Codex is not changing as part of this release.