ChatGPT Use Falls Below 50% as Gemini and Claude Rise

Sensor Tower’s State of AI 2026 report shows ChatGPT’s share of the AI assistant market fell below 50% in March and stood at 46% in May. Google’s Gemini held a 28% share and Anthropic’s Claude reached 10% for the same month.

The report notes OpenAI’s ChatGPT app exceeded 1 billion monthly users in May, becoming the fastest app to reach that milestone. Sensor Tower records activity on apps and sites to calculate market share and audience size.

Google has published its own user counts for Gemini, reporting 750 million monthly users in February and more than 900 million by May. Sensor Tower’s external tracking, which measures activity on Gemini’s app and site, recorded about 662 million users for May. The difference reflects the use of internal platform integrations versus standalone app and site activity.

Sensor Tower identified a rise in Claude’s U.S. share, from about 5% in December to roughly 14% in May. The firm found that Claude’s U.S. downloads increased in early March at the same time Anthropic declined a U.S. Department of Defense request to remove certain safety controls. Sensor Tower reported ChatGPT uninstalls in the U.S. spiked roughly 200% above average the week of March 9, and that Claude out-downloaded ChatGPT for five consecutive days that month before ChatGPT’s lead recovered.

The report highlights platform-specific user skews. Grok, the assistant embedded in X Premium, has the largest tilt toward cryptocurrency traders: Grok users are about four times more likely than the general population to trade crypto. Sensor Tower links that skew to Grok’s integration with live posts on X, which allows it to pick up real-time sentiment around trending tokens, and to the platform’s existing user base.

Sensor Tower also measured differences in monetization. Claude’s average revenue per U.S. mobile user rose from under $0.50 in September to $2.76 in May. ChatGPT’s average revenue per U.S. mobile user was $1.74 in May. The report shows about 13% of Claude’s users subscribed, the highest subscription conversion rate among the assistants measured.

The report attributes several market shifts to distribution, default settings and targeted user niches rather than to performance comparisons. It notes Google’s integration of Gemini across Android, Search, Chrome and Workspace increases exposure beyond the standalone app. OpenAI is pursuing product expansions that bundle shopping and agent features while preparing for a public offering.

Sensor Tower’s figures document changing shares and user behavior across AI assistants through May 2026 without making performance rankings.