More than 50 percent of Facebook’s monthly active users are on mobile apps

by Phil Hornshaw

We already knew Facebook’s various mobile apps were popular, be they on Apple’s iPhone or iPad, on devices running Google’s Android operating system, or even on BlackBerry devices and feature phones.

But the company hadn’t released the exact numbers on its mobile “monthly active users” (MAUs) since September, as TechCrunch reports, when it revealed that it had about 350 million mobile MAUs. But with the filing of Facebook’s initial public offering this week, the company also revealed that in December it reached 425 million mobile MAUs, out of 845 million monthly active users across all platforms.

That’s better than half of everyone logging-in to Facebook during the month of December doing so from devices that were not PCs, and while there are a lot of devices that make up that number, undoubtedly a large portion of those 425 million users are using iOS devices (and another big chunk on Android devices). Mobile Facebook is as important as the original, PC-accessed web-based version, and that suggests the company will be continuing to put a lot of work into keeping its mobile experience strong.

Facebook defines mobile MAUs as anyone who logs-in from a mobile app or using a mobile version of a web browser during the measurement month. So the numbers include mobile app users as well as anyone who uses an iPhone’s Mobile Safari, for example, to log in as well.

Mobile usage increased during 2011, Facebook said, following trends of greater mobile device use in big markets like the U.S. As smartphones achieve greater penetration – smartphones now account for 50 percent of all cellular phones in the U.S. – more of those smartphone owners make use of mobile Facebook apps. The company also said that more people are using mobile versions of Facebook because it is making improvements to the experience. As TechCrunch reports, the release of Facebook’s iPad app in October, after years of waiting, helped spur growth for the company in mobile users.

With such huge numbers, users can probably expect some major changes in the mobile version of Facebook in the future. Many users (although Facebook doesn’t say exactly how many) access the social network purely through its mobile portals, and Facebook doesn’t offer ads on any of the mobile means of accessing the site. That’s a huge advertising market Facebook is currently not reaching, and it’ll likely be looing to dig into it going forward.

Because there are so many users for Mobile Facebook, though, ads are unlikely to be the only thing that Facebook adds to its smartphone apps and mobile web portals. Expect the company to continue to refine the Facebook experience for more devices than just PCs. You’ll have more ads to deal with when you log-in to Facebook on your iPhone, but it’s likely that Facebook will be an easier and more refined experience.