Over half of Facebook users access the service only on mobile

51.7 percent of Facebook users now access the social network exclusively from a mobile device.

More specifically, in its fourth quarter 2015 earnings announcement today, Facebook revealed it now has 1.59 billion monthly active users (up 14 percent year-over-year), and 1.44 billion are monthly mobile users (up 21 percent year over year). Facebook also shared that it now has 1.04 billion daily active users (a 17 percent bump year over year) and 934 million mobile daily active users (a 25 percent increase year over year).

Put another way, 65.41 percent of all Facebook members use the service daily, and 64.86 percent of mobile members use it daily as well. But in its earnings slides (PDF), the company also shared it has 823 million mobile-only users, the most interesting user figure that comes out of its earnings reports.

Between Q3 and Q4, Facebook added 96 million mobile-only users. In Q3 2015, mobile-only users accounted for 46.90 percent of the social network’s total members, so the group grew over 4 percentage points. This number climbs every quarter, though it will naturally slow down soon.

Here is how Facebook distinguishes this category of users:

Mobile-only MAUs are defined as users who accessed Facebook solely through mobile apps or mobile versions of our website, or used our Messenger app, in the last 30 days of the given quarter. The number of mobile-only MAUs do not include Instagram users unless they would otherwise qualify as such users based on their other activities on Facebook.

Even though Facebook doesn’t break out this number in its earnings release, this is by far the most important the one to watch. Facebook’s growth will continue to slow due to its size, but the revenue share coming from mobile is still growing.

In fact, Facebook shared that in Q4 2015, mobile advertising revenue represented approximately 80 percent of all of the company’s advertising revenue. In Q3 2015, that number was 78 percent, and in Q4 2014 it was 69 percent.

Mobile-only users are key to a social network that has managed to successfully transform itself into a mobile-first business. But it’s also impressive that Facebook has managed to keep all its numbers growing, albeit slowly.