OpenAI rolls out ChatGPT 5.1 with two different models

OpenAI has announced the rollout of GPT-5.1, an upgraded version of its GPT-5 series, featuring two key models, GPT-5.1 Instant and GPT-5.1 Thinking. The update aims to improve intelligence, communication, and personalisation across ChatGPT.

According to the company, GPT-5.1 Instant is designed to deliver faster and more conversational responses while better following user instructions. It also introduces ‘adaptive reasoning,’ allowing the model to decide when to take additional time for complex queries, which reportedly improves performance in coding and math evaluations.

GPT-5.1 Thinking, its advanced reasoning model, has been updated to provide clearer, less technical responses. It now adjusts its processing time based on task complexity, offering quicker replies for simple questions and deeper reasoning for complex ones. The company stated that the model’s tone is also designed to be warmer and more empathetic.

The new update also introduces enhanced tone and style controls, enabling users to personalise the AI chatbot’s communication style. These include adjustable traits such as warmth, conciseness, and emoji usage. The company said that the AI chatbot can now proactively suggest updates to tone during conversations, making customisation more intuitive.

Both models are being rolled out gradually, starting with paid users, before expanding to free and logged-out accounts. The API versions of the models are expected later this week. Previous GPT-5 models will remain available for three months under a legacy option to allow users time to transition.

The company noted that the update reflects ‘meaningful improvements’ while remaining part of the GPT-5 generation, with future versions expected to follow a similar naming structure.