• by Mark Walsh  @markfwal, July 3, 2012

Facebook’s initial public offering heightened awareness that its mobile growth was outpacing its overall growth, to the tune of 500 million mobile users worldwide. Reflecting that shift toward device-based use, Facebook is updating reach of a brand’s page posts to include mobile data.

Starting today, mobile distribution will count toward a page’s total reach, according to the Inside Facebook blog. Previously, the measurement of reach was limited to the desktop. “However, it seems Facebook will report reach as a combined total, rather than distinguishing between desktop and mobile,” according to the blog.

Separately, the desktop news feed will no longer count reach until users scroll and load a brand’s post. Facebook will load fewer updates to the feed at a time. Since impressions and reach are counted upon load, the metrics previously included impressions that users might not have actually seen. The idea is to count only viewed impressions as people scroll updates.

So when it comes to reach, it sounds like Facebook giveth and taketh away. On the one hand it may expand a brand’s audience by adding in mobile data, but limit reach through the change to the news feed. How reach shakes out could vary by brand, depending on factors like the share of Facebook traffic coming from mobile .