OpenAI has updated the default model for ChatGPT to GPT-5.5 Instant, replacing GPT-5.3 Instant across all user tiers. The upgrade delivers improved accuracy, reduced hallucinations—particularly in high-stakes domains like medicine, law, and finance—and enhanced performance in image analysis, STEM question-answering, and decision-making around web search use. According to OpenAI, responses are now 'tighter and more to-the-point without losing substance,' with less reliance on emojis, excessive formatting, and follow-up questions, while preserving ChatGPT’s personality.
What it does
GPT-5.5 Instant introduces several functional improvements:
- Higher accuracy and fewer hallucinations: Especially notable in technical and regulated fields.
- Better multimodal reasoning: Improved image analysis capabilities, building on the foundation of ChatGPT Images 2.0 released April 22, 2026.
- Smarter tool use: More autonomous decisions about when to trigger web search for up-to-date information.
- STEM proficiency: Stronger reasoning in science, technology, engineering, and math queries.
- Contextual awareness: Enhanced ability to draw from user history, files, and Gmail for personalized responses—though this feature is currently limited to paid subscribers (Plus and Pro tiers on the web).
All ChatGPT models are being updated with memory sources, a transparency feature that shows users which past chats, files, or context were used to generate a given response.
Availability and access
GPT-5.5 Instant rolled out on May 5, 2026, to all ChatGPT users, including free-tier accounts. However, personalization using Gmail, files, and chat history is initially available only to Plus and Pro subscribers on the web. OpenAI states that this capability will expand to mobile platforms soon and will be extended to Free, Go, Business, and Enterprise users in the coming weeks.
The upgrade follows the April 24, 2026 release of the full GPT-5.5 model, which OpenAI described as more capable in agentic coding, computer use, and early-stage scientific research. GPT-5.5 Instant appears to be a streamlined variant optimized for speed and efficiency while retaining core advancements.
The $100/month Pro subscription tier, introduced April 9, 2026, offers 5x more Codex usage than the $20/month Plus plan and is targeted at users running long, high-effort coding sessions with OpenAI’s AI coding agent.
It remains unclear when Apple Intelligence’s integrated ChatGPT functionality will transition from GPT-5.3 Instant