Google revealed a handful of milestones during its I/O 2019 developer conference in Mountain View today, but the biggest was undoubtedly that Android now powers 2.5 billion active devices.

“We’re here to talk about Android version, 10, and we get to celebrate a milestone together,” Android product manager Stephanie Cuthbertson said onstage. “Today there are over 2.5 billion active Android devices.”

The last time Google reported on this figure was also at I/O, in May 2017, when Android passed 2 billion monthly active devices . Google thus managed to add some 500 million devices in 24 months, or about 20 million devices per month. In September 2015, Android had 1.4 billion active users . People can of course use multiple devices and multiple accounts, so the number of users is likely lower than 2.5 billion. Nonetheless, the growth is impressive.

10 years and now over 2.5 billion active devices. Thanks for joining us on this journey. #io19

— Android (@Android) May 7, 2019

Let’s put that into context. That’s more than the 1.5 billion PCs that Microsoft estimates are running Windows worldwide, a figure that hasn’t been updated in years. It’s also more than Facebook’s 2.38 billion monthly active users , as of last month.

Android was the company’s first platform to reach the 2 billion mark. For a while now, Google has pointed out that it has eight products with more than a billion users: Android, Chrome, Google Play, Gmail, Google Drive, Google Maps, Google Search, and YouTube. But Android remains way ahead of the pack.