On November 12, 2025 (local time), OpenAI officially launched its latest flagship model—the GPT-5.1 series. This series comprises two primary variants: GPT-5.1 Instant and GPT-5.1 Thinking. Alongside these, the GPT-5.1 Auto intelligent feature was also introduced simultaneously. The rollout of these new models will commence for paying users from today, with free users gaining access once the paying user rollout is fully completed. API developers can expect to access GPT-5.1 later this week.

GPT-5.1 Instant incorporates a novel "adaptive reasoning" mechanism. This system autonomously evaluates the complexity of user inquiries, ensuring swift responses for straightforward questions while automatically delving into deeper analysis for more intricate tasks. Moreover, it adopts a more amiable and engaging conversational tone, with a marked improvement in its ability to accurately follow user instructions.

GPT-5.1 Thinking, on the other hand, facilitates intelligent adjustment of its thinking pace. It doubles the response speed for simple tasks compared to its predecessor and extends the thinking period for complex issues to generate detailed and comprehensive answers. Additionally, it significantly reduces the use of technical jargon and obscure terminology.

GPT-5.1 Auto is designed to automatically select the most appropriate model for each user query, optimizing the user experience. Furthermore, GPT-5.1 introduces an eight-dimensional dialogue style matrix, catering to a wide range of scenarios including work, social interaction, and creative endeavors. Users are also empowered to customize details such as answer brevity and the warmth of the conversational tone.

To mitigate potential user adaptation challenges, OpenAI offers a "second chance" option. This allows paying users to revert to the older GPT-5 version within the settings for up to three months, ensuring a smooth transition for those who may prefer the previous iteration.