OpenAI's GPT-5.1 Update Introduces Enhanced Reasoning And User Personalization For ChatGPT

OpenAI has introduced GPT-5.1, an update to its GPT-5 series, enhancing reasoning, conversation quality, and user personalization. This update includes two models: GPT-5.1 Instant and GPT-5.1 Thinking. These models aim to provide a more adaptable and user-friendly ChatGPT experience, improving both intelligence and usability.

Enhanced User Experience

GPT-5.1 Instant is the most frequently used model in the ChatGPT lineup. It now offers responses in a friendlier tone and follows instructions more accurately. The model's adaptive reasoning allows it to spend more time on complex questions, providing detailed answers while maintaining quick response times. Initial tests indicate improved performance in math and coding tasks, such as AIME 2025 and Codeforces.

Meanwhile, GPT-5.1 Thinking is tailored for intricate reasoning tasks. It adjusts its processing time based on question complexity, delivering quicker replies for simple queries and more comprehensive answers for challenging ones. Compared to its predecessor, it is twice as fast on easy tasks but takes longer on difficult ones. Responses are clearer with less technical jargon, adopting a warmer tone.

Key Features of GPT‑5.1

The new version boasts several key features aimed at enhancing user interaction. Adaptive Model Routing automatically directs queries to the most suitable model for the task at hand. Users can choose from six chat styles: Default, Friendly, Efficient, Professional, Candid, and Quirky. Additionally, legacy styles like Cynical and Nerdy remain available.

Fine-tuning controls allow users to adjust response conciseness, warmth, scannability, and emoji usage according to their preferences. ChatGPT can also proactively suggest updates to tone and style during conversations. Personalization updates take effect immediately across all chats.

Improved Customization

The update enhances adherence to custom instructions by providing precise control over response tone and behavior for both Instant and Thinking models. This ensures that users have a tailored experience that aligns with their specific needs.

Looking forward, OpenAI plans to continue refining GPT-5.1's intelligence and usability features. Future updates will focus on further improving reasoning capabilities, conversational quality, and personalization options to make ChatGPT even more adaptable to individual preferences.

Availability Details

The rollout of GPT-5.1 Instant and GPT-5.1 Thinking begins with paid users (Pro, Plus, Go, Business), followed by free users and those not logged in. Enterprise and Education plans offer a seven-day early-access toggle (off by default). Eventually, GPT-5.1 will become the default model for all users.

Legacy GPT-5 models will remain accessible to paid users for three months after the release of GPT-5.1 Instant and Thinking models are added to the API as gpt-5.1-chat-latest and gpt-5.1 respectively; both support adaptive reasoning capabilities.