OpenAI says ChatGPT reaches 800 million weekly active users

Sam Altman said ChatGPT had reached more than 800 million weekly active users, announcing the figure during his opening keynote at OpenAI’s DevDay in San Francisco. It was, as reported at the time, roughly double the combined weekly user counts OpenAI’s leading rivals had disclosed, and represented sustained growth over the year: OpenAI had cited around 400 million weekly active users in February 2025 and around 700 million by August, meaning the total roughly doubled over the eight months to October.

Altman paired the figure with developer-side metrics: the number of developers building on OpenAI’s platform had grown from 2 million to 4 million since the company’s first DevDay in 2023, and API token throughput had risen from around 300 million tokens per minute to more than 6 billion.

The user figure was self-reported and not independently audited, as with prior OpenAI adoption claims — “weekly active users” is a metric OpenAI defines and discloses on its own terms, without third-party verification of methodology. It nonetheless served as the clearest available signal of ChatGPT’s scale relative to competitors, and framed the developer tools OpenAI unveiled at the same event as reaching an unusually large existing audience rather than needing to build one from scratch. This October DevDay announcement was the original milestone; an OpenAI enterprise-adoption report published that December cited the same 800-million figure again rather than reporting further growth.