OpenAI has unveiled a new model for ChatGPT known as GPT-5.5 Instant, replacing the previous GPT-5.3 Instant. The organisation asserts that this latest AI model diminishes hallucinations and improves the accuracy of responses for everyday use. It is designed to enhance user interactions with the AI chatbot, positively impacting a vast number of users daily.
The GPT-5.5 Instant model promises even more precise and sophisticated responses across various topics. Users can expect a more human-like and fluid interaction, with greater personalisation tailored to their specific context.
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Highlights
Performance and Improvements of GPT-5.5 Instant
According to a press release from OpenAI, the GPT-5.5 Instant model features a reduction of 52.5% in hallucinated claims compared to GPT-5.3 Instant. Additionally, inaccuracies have diminished by 37.3%, thanks to enhancements driven by user feedback.
OpenAI highlighted that the GPT-5.5 Instant model is smarter and more competent across routine tasks. This includes advancements in analysing photos and images, addressing STEM-related inquiries, and discerning when it is appropriate to utilise web searches to provide more beneficial answers.
Benchmark Testing Results
In benchmark evaluations, the performance of the GPT-5.5 Instant model stands out. On the AIME 2025 math benchmark, it achieved a score of 81.2 points, significantly up from the prior score of 65.4 points. In the MMMU-Pro multimodal reasoning benchmark, it scored 76 points, an improvement from 69.2 points previously. This reflects the model’s capabilities in mathematics, logical reasoning, and multimedia processing.
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Memory Source Features in OpenAI’s AI Models
GPT-5.5 Instant also introduces the functionality of referencing context from previous chats, files, and Gmail, allowing users to receive personalised and relevant responses. Moreover, OpenAI is implementing a novel feature termed “memory sources”, which provides context regarding memories or earlier conversations that have shaped a response. Users can review this information and have the option to amend or remove any outdated or irrelevant content.
Users hold the authority to decide what to retain as Memory Sources. They can delete chats, revise saved memories, or opt for temporary chats that do not store or leverage memory at all.
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Availability of GPT-5.5 Instant
The GPT-5.5 Instant model is being rolled out as the default for all ChatGPT users, and is also available in the API as chat-latest. The GPT-5.3 Instant will continue to be accessible to paid users for a period of three months before it is phased out.