OpenAI Replaces ChatGPT’s Default Model With GPT-5.5 Instant

OpenAI rolled out GPT-5.5 Instant as the new default model in ChatGPT, replacing GPT-5.3 Instant with a version designed to improve accuracy, reduce hallucinations, and maintain low response latency. The update is now available to all users and introduces enhancements across reasoning, clarity, and personalization features.

The model builds on the broader GPT-5.5 release from last month, with OpenAI pointing to gains in coding and general knowledge tasks. Benchmark results show measurable improvements, including a higher score on the AIME 2025 math test and stronger performance on the MMMU-Pro multimodal reasoning benchmark compared to the prior version.

A central change in this release is how the model handles context. For Plus and Pro users on the web, GPT-5.5 Instant can pull from past conversations, saved memories, files, and connected Gmail accounts to generate more relevant responses. The system is also faster at retrieving prior context, reducing the need for users to restate information across sessions.

OpenAI is also introducing “memory sources,” a feature that shows what inputs contributed to a response. Users can review, edit, or remove this information, while the company notes that these sources remain private and are not visible when chats are shared.

The update also targets reliability in high-stakes domains such as law, medicine, and finance, while reducing unnecessary follow-up questions and overly formatted responses.

GPT-5.5 Instant is rolling out immediately, with GPT-5.3 Instant remaining available for paid users for a limited period before being retired.

This analysis is based on reporting from OpenAI and TechCrunch.

Image courtesy of OpenAI.

This article was generated with AI assistance and reviewed for accuracy and quality.