OpenAI says GPT-5 hallucinates less — what does the data say?

OpenAI has officially launched GPT-5 , promising a faster and more capable AI model to power ChatGPT .

The AI company boasts state-of-the-art performance across math, coding, writing, and health advice. OpenAI proudly shared that GPT-5's hallucination rates have decreased compared to earlier models.

Specifically, GPT makes incorrect claims 9.6 percent of the time, compared to 12.9 percent for GPT-4o. And according to the GPT-5 system card , the new model’s hallucination rate is 26 percent lower than GPT-4o. In addition, GPT-5 had 44 percent fewer responses with “at least one major factual error.”

While that's definite progress, that also means roughly one in 10 responses from GPT-5 could contain hallucinations. That's concerning, especially since OpenAI touted healthcare as a pro