OpenAI Rolls Out GPT-5.5 Instant as Default, Retires Older ChatGPT Models

OpenAI has announced a significant update to ChatGPT, designating GPT-5.5 Instant as the new default model for all users. This strategic move aims to elevate the everyday user experience by delivering stronger, more accurate, and clearer responses across various subject areas. GPT-5.5 Instant is designed to offer a more natural conversational tone and better leverage contextual information shared by users, leading to more personalized and helpful interactions. This new default model replaces the previous GPT-5.3 Instant, which will remain accessible to paid users for a limited period before its eventual retirement. OpenAI emphasizes that GPT-5.5 Instant shows marked improvements in factual reliability, particularly in high-stakes domains like law, finance, and medicine, where accuracy is paramount. The model also demonstrates enhanced capabilities in analyzing image uploads and handling STEM-related queries, alongside an improved ability to discern when to utilize web search for more comprehensive answers. In conjunction with the rollout of GPT-5.5 Instant, OpenAI is also phasing out several older models to optimize its resources and concentrate on its most advanced AI. OpenAI o3 is slated for retirement from ChatGPT on August 26, 2026, following a 90-day sunset period. Similarly, GPT-4.5 will be retired on June 27, 2026, after a 30-day sunset period. These older models were primarily available to paid users through model settings. These changes are specific to ChatGPT and do not affect the API. The company's focus remains on continually refining its cutting-edge models to provide the most effective and efficient AI tools.