SAN FRANCISCO, CALIFORNIA / Content Syndication Services / — OpenAI’s ChatGPT reached 1 billion monthly active app users worldwide in May 2026, according to data from market intelligence firm Sensor Tower, marking the fastest rise to that level recorded for a consumer app. The estimate places ChatGPT among the largest digital platforms by app usage less than four years after OpenAI introduced the chatbot in November 2022, extending one of the steepest adoption curves in consumer technology.
Sensor Tower said ChatGPT reached the 1 billion monthly active user mark faster than major mobile platforms that previously defined app-scale growth, including Google Maps, TikTok, Instagram and YouTube. The firm’s measurement refers to monthly active app users globally, a metric distinct from website traffic, downloads and weekly active user counts. The data adds a mobile usage benchmark to prior disclosures that had already shown ChatGPT moving from early adoption into mainstream consumer use.
OpenAI had separately said in February 2026 that ChatGPT had more than 900 million weekly active users and more than 50 million consumer subscribers. Those figures were based on OpenAI’s own usage disclosures, while the new 1 billion monthly active app user figure is an external market estimate from Sensor Tower. Together, the figures show broad global use of ChatGPT across free accounts, paid subscriptions and mobile app access.
App milestone follows rapid download growth
The latest app usage milestone follows an earlier Sensor Tower finding that ChatGPT became the fastest app to reach 1 billion global downloads across iOS and Google Play in July 2025. Sensor Tower also reported that ChatGPT had previously become the fastest app, excluding preinstalled applications, to reach 500 million monthly active users. Those earlier benchmarks indicate that ChatGPT’s mobile audience expanded beyond initial groups such as students, developers and workplace users.
Sensor Tower’s AI app research has also tracked a broader increase in generative AI app use. In its 2025 analysis, the firm said user activity in AI assistant apps had spread across more consumer categories, with ChatGPT prompts increasingly covering lifestyle and entertainment uses alongside work, education, coding, writing and translation. The report said ChatGPT’s weekend usage pattern had become closer to mainstream consumer apps than to workplace-focused tools.
Claude gains as ChatGPT remains larger
The figures also show a widening competitive field for AI assistant apps. Sensor Tower estimated Anthropic’s Claude had 56 million global monthly active app users in the second quarter to date. The firm estimated Claude’s year-over-year growth in monthly active users at about 640 percent, compared with 62 percent for ChatGPT, while ChatGPT remained much larger in total app users. Anthropic and Claude are directly competing with OpenAI and ChatGPT in consumer and workplace AI tools.
Sensor Tower also reported a user-overlap signal in the United States, saying ChatGPT users who installed Claude in the first quarter of 2026 spent 5 percent less time on ChatGPT one month after installing Claude compared with their average over the previous eight months. The finding measures observed app engagement among those users and does not identify reasons for the change. The data places ChatGPT’s 1 billion user milestone within a larger shift toward regular consumer use of AI assistants.