OpenAI has rolled out GPT-5.5 Instant as the new default model for all ChatGPT users, according to the company's announcement.
A New Standard for Accuracy
The centerpiece of the update is a reduction in hallucinations — instances where the model generates plausible but incorrect information. Per OpenAI's announcement, GPT-5.5 Instant cuts hallucination rates by more than 40% compared to its predecessor.
Enhanced Personalization and Control
OpenAI also details several personalization changes in the release:
- Improved Contextual Memory: The model retains context from longer conversations more effectively, producing more coherent follow-up responses.
- Finer-Grained Style Controls: Users can more precisely direct tone, style, and formatting.
- Reduced Biases: OpenAI says it has made progress mitigating biases in model outputs.
- Faster Responses: The company says the model is optimized for speed despite added capability.
These changes apply to ChatGPT's default experience as of the rollout; OpenAI has not specified a timeline for extending the update to API users.