OpenAI has released GPT 5.1 and is deploying it inside ChatGPT as the updated default model family, with two primary variants called GPT 5.1 Instant and GPT 5.1 Thinking. ChatGPT also adds expanded personality controls that allow users to change response style during an ongoing conversation, and OpenAI describes adaptive reasoning that adjusts how much time the system spends on a prompt.
What GPT 5.1 changes in ChatGPT
GPT 5.1 is presented as an update focused on instruction following, conversational clarity, and responsiveness, based on the product descriptions published alongside the rollout. the official report describes GPT 5.1 Instant as the default experience for most queries, while GPT 5.1 Thinking is positioned for more complex tasks that benefit from a longer reasoning approach. OpenAI’s product post also frames GPT 5.1 Instant as the most used mode and describes improvements to how ChatGPT follows custom instructions and maintains a more conversational style.
Instant replies and Thinking Modes
GPT 5.1 Instant is positioned as the faster option intended for everyday questions and routine tasks inside ChatGPT. GPT 5.1 Thinking is described as a more deliberative option for complex tasks, with emphasis on clearer communication and reduced jargon compared with prior behavior described in the TechRadar report. The OpenAI product post describes both variants rolling out together and indicates that users may not see availability immediately due to a gradual deployment approach.
Adaptive Reasoning to increase versatility
OpenAI has stated that ChatGPT applies adaptive reasoning to decide when to respond quickly and when to take additional time for a prompt. The OpenAI product post describes a related approach where the system can vary the amount of thinking time based on the prompt, alongside the introduction of GPT 5.1 Instant and GPT 5.1 Thinking. The available source material does not provide independent benchmark results, and it does not include a standardized measurement method for the adaptive reasoning behavior beyond product descriptions.
Personality controls and tone settings
OpenAI is expanding personalization options in ChatGPT, with tone and style controls intended to apply immediately across chats, including ongoing conversations. The TechRadar report states that users can adjust manner and style in real time and describes a broader set of tone options, with changes taking effect without starting a new chat. OpenAI’s product post also states that updates in personalization settings take effect across all chats right away, which includes changes made during an ongoing conversation.
Release and Availability
OpenAI’s product post describes GPT 5.1 rolling out starting with paid users first, then expanding to additional user categories as deployment progresses. The product page also states that paying subscribers receive GPT 5.1 as the default and indicates a later expansion to other users, along with continued availability of older models for a limited period.
