OpenAI's New GPT-5.5 Instant: ChatGPT's Default Model, Cuts Hallucinations by 52.5%

SAN FRANCISCO, May 5. Leading artificial intelligence company OpenAI has released a new default model for its popular chatbot ChatGPT—GPT-5.5 Instant. The new model replaces the previous GPT-5.3 Instant, and its biggest focus is reducing one of AI's oldest problems: "hallucination," or confidently giving wrong or fabricated information. The company claims the model produces 52.5% fewer false claims than its predecessor on high-stakes prompts. With hundreds of millions of people worldwide using ChatGPT for everyday tasks, study and professional needs, the update is set to have a very wide impact.

A dramatic drop in hallucinations

The main aim of the release is to improve accuracy in sensitive areas such as medicine, law and finance. According to OpenAI, hallucination rates in these domains have dropped from roughly 20% to around just 3%. This improvement is hugely important for users who rely on AI for serious decisions, since the consequences of wrong information can be severe in these fields. Hallucination has long been considered one of AI's biggest weaknesses, and it is why many institutions have hesitated to adopt these tools for sensitive work.

Better reasoning and multimodal performance

GPT-5.5 Instant not only makes fewer errors but has improved overall capabilities. It scored 81.2 on the AIME 2025 maths test, compared with 65.4 for the older model. Similarly, it recorded a score of 76 on the MMMU-Pro multimodal reasoning benchmark, well above the older model's 69.2. The model now gives more accurate, concise and natural answers across a wide range of subjects. Notably, these gains were achieved without affecting the model's speed—the fast response time is the main appeal of an "Instant" model.

A new 'memory sources' feature

On personalization, OpenAI has added a new 'memory sources' feature. It shows users which personal context—past chats, saved reminders or uploaded files—informed a given response. Users can also correct or remove these individual entries, increasing both transparency and control. At a time when concerns about AI and data privacy are rising, this feature is a welcome step toward giving users more control over their data.

API access for developers

For developers, GPT-5.5 Instant is available in the API as "chat-latest," while the older GPT-5.3 model will remain available to paid users for three months. This gradual transition ensures existing applications and services can migrate to the new model without sudden disruption. As of June 9, personalization improvements have also rolled out to users on the ChatGPT Go and Free tiers. Thousands of startups and companies worldwide build products on OpenAI's API, so every change to the default model has wide-reaching effects.

OpenAI's strategy in the AI race

The release comes at a time when competition between AI models is intense and reliability has become a key issue. By emphasizing reduced hallucination, OpenAI is targeting the business and professional users who need accuracy most. The company also released GPT-Realtime-2 in May, and there is speculation about GPT-5.6 in June, reflecting its rapid pace of innovation. In this race with Google, Anthropic and other rivals, every company is striving to prove its model the most accurate and trustworthy.

What's next

With GPT-5.5 Instant as the default, hundreds of millions of ChatGPT users will now get a more reliable and personalized experience. Better accuracy in sensitive areas brings AI closer to high-stakes uses such as health, legal and financial advice, though experts still stress the need for human oversight. In the coming months, it will be important to see how rival companies respond and how far this race for AI reliability goes. For now, GPT-5.5 Instant is seen as an important step in that direction, moving AI toward becoming a more dependable part of everyday life.

Significance for Indian users

India is among the largest user bases for ChatGPT globally, and improvements to reliability matter greatly here. Students, small businesses, developers and professionals across the country increasingly turn to the chatbot for research, coding, drafting and learning. Reduced hallucination in fields like law, medicine and finance is especially valuable in a market where access to expert advice can be limited and costly, though the tool is no substitute for qualified professionals. The model's stronger reasoning and multilingual handling also benefit India's diverse linguistic landscape. As enterprises and government bodies explore generative AI for public services, education and productivity, a more accurate default model lowers the risk of errors and builds the trust needed for wider adoption. The update therefore lands at a moment when AI is rapidly weaving itself into India's digital economy.