OpenAI is replacing GPT-5.3 Instant with GPT-5.5 Instant as the default ChatGPT model, and the update focuses on the things users notice fastest: clearer answers, fewer made-up claims, less clutter, and fewer unnecessary follow-up questions.
GPT-5.5 Instant Is Now the Default ChatGPT Model
OpenAI says GPT-5.5 Instant starts rolling out today to all ChatGPT users, with paid users keeping access to GPT-5.3 Instant for three more months through model settings. The new model also arrives in the API as chat-latest.
OpenAI framed the update as a practical improvement for everyday ChatGPT use, especially because Instant is the model most people use by default.
OpenAI said, “We’re updating ChatGPT’s default model, available to everyone, to be smarter and more accurate, with clearer, more concise answers that feel better tailored to you. Because Instant is the daily driver for hundreds of millions of people, small improvements make a big difference. This update makes everyday interactions more useful and more enjoyable: stronger and tighter answers across subject areas, a more natural conversational tone, and better use of the context you’ve already shared when personalization can help.”
Fewer Hallucinations
The biggest claim here is accuracy. OpenAI says GPT-5.5 Instant produced 52.5% fewer hallucinated claims than GPT-5.3 Instant on high-stakes prompts covering medicine, law, and finance. It also reduced inaccurate claims by 37.3% on difficult user-flagged conversations.
That matters because ChatGPT does not just answer casual questions anymore. People use it for coding, documents, research, schoolwork, planning, image analysis, and workplace writing. A model that gives “tighter and more-to-the-point” responses also saves users from sorting through long answers that say more than needed.
OpenAI also says GPT-5.5 Instant uses past chats, files, and connected Gmail more effectively when those sources are available. The company is adding memory sources, so users can see which saved memories or past chats helped shape a personalized answer.
For users, the update means ChatGPT should feel less bloated, more accurate, and more aware of context without turning every answer into a long explanation.
