Gmail becomes the sixth Google service to cross the 1 billion barrier, while WhatsApp becomes Facebook’s second most-used app

Facebook’s WhatsApp messenger and Google’s Gmail have both crossed the 1 billion monthly active user milestone, meaning that one-seventh of the world’s population now uses them both.

The two apps join Facebook’s 1.59 billion monthly active users (MAU), as well as Google’s other 1 billion or more MAU services: Google search, Chrome (both mobile and desktop), Google Maps, YouTube, Google’s Android and therefore also Google Play.

For Facebook, which has 1.44 billion mobile monthly users of its main social networking app, the purchase of WhatsApp was predicated on a belief that the app was on track to be used by 1 billion people globally – an elite club of very few apps and services.

Mark Zuckerberg, chief executive of Facebook said at the time of the purchase: “WhatsApp is on a path to connect 1 billion people. The services that reach that milestone are all incredibly valuable.”

WhatsApp is used in both the developed and developing world, available across almost every platform and comes pre-installed on many feature phones used across the developing world, where smartphone penetration is still low.

Google’s Gmail, however, is a more resource-intensive application than WhatsApp despite having low-bandwidth versions of its webmail service. But the Gmail Android app crossed the billion installs mark in May 2014, becoming the first one to hit that milestone, with Facebook behind.

According to Google, there are 1.4 billion active Android users per month, but that does not include all the devices that do not use Google’s version of Android, of which China and its 900 million-plus smartphone users make up a large proportion.

For comparison, there were 1.5 billion users of Windows in 2014 according to Microsoft, and there are currently 1.2 billion users of the company’s Office suite. There are also estimated to be 1.4 billion households with at least one television globally, according to data from the UN’s International Telecommunication Union.

There are also 3.2 billion people with an internet connection across the globe, according to the ITU, which is only set to increase as the proliferation of mobile internet continues, while the global population stands at 7.4 billion people.

For Google, users of its apps including Gmail are potential eyeballs for its advertising business, but the business case for Facebook’s WhatsApp, which recently announced that it would waive its yearly $0.99 fee, is less clear. WhatsApp committed to staying advertising free, and there is no formal link within the app between Facebook and WhatsApp.

Facebook also has its Messenger platform, a spin-off from its main social network, which had 800 million monthly active users by the end of last year. The two messaging platforms undoubtedly have an overlapping market, but WhatsApp has greater appeal in the developing world. How much that is worth to Facebook is uncertain.