GPT-5.5 Instant - OpenAI's next-generation default model for ChatGPT.

What is GPT-5.5 Instant?

GPT-5.5 Instant is the next-generation default model for ChatGPT released by OpenAI, replacing GPT-5.3 Instant, and is freely available to all users. The model combines the basic intelligence and rapid response of GPT-5.5, reduces hallucinations in high-risk domains by 52.5%, and offers more concise answers (30% fewer words) and a more natural tone. A new "Memory Source" feature allows users to view and manage their personal memories; Plus/Pro users can access historical conversations and Gmail for personalization.

Main functions of GPT-5.5 Instant

• The rate of hallucinations has decreased significantly.False statements in high-risk areas (medical, legal, financial) decreased by 52.5%, and the inaccuracy rate of historical erroneous dialogues decreased by 37.3%.
• A more concise and natural answerReduce redundant formatting, unnecessary follow-up questions, and excessive emojis; reduce word count and line count by approximately 30% while maintaining a warm tone.
• Multimodal and tool capability enhancementIt supports photo and image upload analysis, STEM question answering, complex document parsing, and intelligent decision-making for calling search tools.
• The source of memory is transparent and controllableThe "Memory Source" feature has been added, which allows users to view, delete, or correct personal memory entries that affect this reply.
• Deep personalization supportPlus/Pro users can access historical conversations, uploaded files, and linked Gmail accounts to achieve accurate and personalized responses based on context.

Technical Principles of GPT-5.5 Instant

• GPT-5.5 Infrastructure and Inference OptimizationBased on the GPT-5.5 series model architecture, low-latency response is achieved through system-level inference optimization, compressing end-to-end generation time while maintaining basic intelligence, thus balancing speed and quality.
• Factual alignment and hallucination inhibitionEmploying an improved post-training alignment technique, it enhances factual accuracy in high-risk fields such as medicine, law, and finance. Through an internal evaluation mechanism, it reduces hallucination statements by 52.5% and inaccurate statements in tricky conversations by 37.3%.
• Contextual memory retrieval and attributionThe system introduces Memory Sources technology, which allows the model to retrieve relevant historical conversations, uploaded files, and Gmail content when generating responses, and to explicitly attribute these information on the interface. Users can also mark, correct, or delete memory entries based on their relevance.
• Post-style training and expression optimizationBy adjusting post-training to focus on conciseness and a warm tone, excessive formatting, redundant follow-up questions, and meaningless emojis are reduced, resulting in a 30% reduction in the number of characters in replies while maintaining substantial information density and a natural conversational feel.
• Multimodal joint reasoningIt integrates visual-language understanding capabilities to perform joint encoding and reasoning on photos, handwritten formulas, scientific charts, and complex documents, resulting in significant improvements in accuracy on multimodal benchmarks such as CharXiv and MMMU-Pro.

How to use GPT-5.5 Instant

Key information and usage requirements for GPT-5.5 Instant

• Product NameGPT-5.5 Instant
• PublisherOpenAI
• Launch timeMay 6, 2026
• Product PositioningChatGPT is the next-generation default instant model, replacing GPT-5.3 Instant, and is designed for hundreds of millions of everyday users.
• Available rangeFree for all ChatGPT users, API is available. chat-latest supply
• Core upgradeHallucinations in high-risk areas decreased by 52.5%, and the inaccuracy rate of historical error dialogues decreased by 37.3%; the number of characters and lines in responses decreased by approximately 30%; a new transparent management function for "memory sources" was added.
• Benchmark performanceAIME 2025 Math Test 81.2% (+15.8%), GPQA Doctoral Science Reasoning 85.6% (+7.1%), MMMU-Pro 76%, CharXiv 81.6%
• Transitional arrangementsGPT-5.3 Instant will be retained for 3 months for paid users before being officially discontinued.
• Regular usersNo manual operation is required; opening the ChatGPT webpage or app will automatically switch to GPT-5.5 Instant.
• Memory ManagementOn the web chat interface, click "Sources" on the right to view the sources of the memories cited in this reply. You can also mark individual memories as "relevant/irrelevant," click "correct" to update the content, or click "delete" to remove outdated information.

The core advantages of GPT-5.5 Instant

• The rate of hallucinations decreased significantly.False statements in the medical, legal, and financial fields have been significantly reduced, making daily interactions more trustworthy.
• Reasoning ability leapsAIME 2025 Math Test 81.2% (+15.8%), GPQA Doctoral Science Reasoning 85.6% (+7.1%).
• A more natural and warm expressionThe word count has been reduced by approximately 30%, and the number of lines by approximately 29.2%, retaining the essential information while making it feel more like a real conversation.
• Memory is controllable and transparentUsers can see which memories are referenced in their replies, and can correct or delete them at any time to avoid interference from outdated information.
• More personalized and preciseIt proactively recommends information based on past conversations, eliminating the need to repeatedly explain background information such as dietary preferences and frequently visited locations.

GPT-5.5 Instant project address

• Project official websitehttps://openai.com/index/gpt-5-5-instant/

Comparison of GPT-5.5 Instant with similar competing products

Application scenarios of GPT-5.5 Instant

• High-risk professional consultationIn scenarios where accuracy is extremely important, such as interpreting medical symptoms, analyzing legal clauses, and verifying financial data, the hallucination rate was reduced by 52.5%, significantly improving credibility.
• Education and Scientific ResearchIn competitive mathematical problem-solving, scientific graph reasoning, and structured analysis of academic papers, its performance in AIME 2025 and GPQA benchmark tests is significantly better than its predecessor.
• Workplace daily communicationIt supports tasks that require a natural and warm tone, such as composing emails, politely expressing refusal, and taking meeting minutes, and provides concise and uncluttered answers.
• Personalized Lifestyle RecommendationsBased on training goals, dietary restrictions, taste preferences, and historical memories of frequently visited places, it can accurately recommend restaurants, recipes, or travel plans.
• Multimodal content analysisThe model can identify calculation errors in handwritten formulas, interpret complex data charts, extract key information from scanned documents, and supports real-time analysis of uploaded photos and images.