OpenAI just upgraded GPT-5 to GPT-5.1 Instant and GPT-5.1 Thinking in ChatGPT app, delivering responses that are both more intelligent and naturally conversational. GPT-5.1 Instant now incorporates light adaptive reasoning to handle challenging questions while maintaining speed, and GPT-5.1 Thinking adjusts its processing time more precisely for complex tasks while providing clearer, more accessible responses. GPT-5.1 Auto continues directing each query to the most suitable model, while legacy GPT-5 models will remain accessible for three months in the Legacy models dropdown, allowing you to compare performance and transition at your convenience.