OpenAI upgrades ChatGPT's default Instant model with better accuracy and personalization

OpenAI is rolling out GPT-5.5 Instant as the new default model for all ChatGPT users, replacing the previous GPT-5.3 Instant.

Back in March, OpenAI announced GPT-5.3 Instant, an update for one of the most popular GPT models, GPT-5.2 Instant. OpenAI claimed that the new model is more natural, less dramatic in its responses, and reduces the number of unnecessary refusals to users’ questions. Since then, OpenAI has released GPT-5.4 and GPT-5.5 models targeting programmers and power users.

Today, OpenAI announced that it is updating ChatGPT’s default Instant model for all users. The new GPT-5.5 Instant model replaces GPT-5.3 Instant, and OpenAI claims that it will deliver smarter, more accurate, and more concise responses.

GPT-5.3 Instant has been serving hundreds of millions of people every day for over two months now. According to OpenAI, the new GPT-5.5 Instant will have a more natural conversational tone and will make better use of personalized context from past chats, uploaded files, and connected Gmail accounts.

OpenAI claims that one of the biggest improvements in GPT-5.5 Instant is factual accuracy. As per its internal benchmarks, GPT-5.5 Instant produced 52.5% fewer hallucinated claims than GPT-5.3 Instant in medicine, law, and finance. GPT-5.5 Instant also improves performance in image analysis and STEM-related questions, thanks to improvements across visual reasoning, math, and science. For example, in GPQA, GPT-5.5 Instant scored 85.6%; in AIME 2026, it scored 81.2%; and in MMMU-Pro, it scored 76%.

Along with GPT-5.5 Instant, OpenAI announced memory sources across all ChatGPT models. When ChatGPT personalizes a response, users will be able to see some of the context used, such as saved memories or past chats. Users can delete or edit outdated memory information.

GPT-5.5 Instant is rolling out to all ChatGPT users as the new default model. It is also available in the API as chat-latest. As always, for ChatGPT paid users, GPT-5.3 Instant will remain available for three months.

The improved personalization from past chats, files, and connected Gmail is rolling out to Plus and Pro users on the web first. It is coming soon to mobile, with plans to expand to Free, Go, Business, and Enterprise users in the coming weeks. Memory sources are rolling out across ChatGPT consumer plans on the web and will arrive on mobile soon.