ChatGPT Hits 1 Billion Users — But Claude Is Growing 640% Year Over Year

In May 2026, ChatGPT reached a historic milestone: 1 billion monthly active users (MAU), confirmed by Sensor Tower. It's the fastest application in history to achieve this — outpacing Google Maps, TikTok, Instagram, and YouTube.

The numbers

• ChatGPT: 1 billion MAU, 900 million weekly active users
• Claude: 56 million MAU on mobile app
• ChatGPT YoY growth: 62%
• Claude YoY growth: ~640%

The most interesting data point

While ChatGPT won the awareness war, the usage war is still being fought. And Claude is growing at a pace that demands attention.

Sensor Tower also found that US ChatGPT users who installed the Claude app in Q1 2026 spent 5% less time on ChatGPT one month later — a small but measurable shift.

What this means

One billion users is not a ceiling — it's a floor. But Claude's 640% growth, if sustained for even two more years, rewrites the competitive map entirely.

This isn't a one-horse race. It's a market forming, with multiple players growing in parallel — and the end user is the one who benefits from the competition.

Broader context

This milestone comes during a historic moment for the industry: SpaceX making the largest IPO in history, Anthropic and OpenAI filing S-1 with the SEC, and a price war making world-class models increasingly accessible. 2026 is the year AI moved from hype into the real economy.