Change to Facebook Page Tab Widths Officially Begins Today

In what has become one of the most slowly introduced changes to Facebook’s platform, the company is beginning to implement a long-planned tab width reduction on Pages. The official transition begins today, Facebook said earlier this month, following delays that began shortly after the company said it would make the change last October.

Now, the maximum width for any Page tab is 520 pixels, down from 760 pixels. Applications and canvas pages will need to be reformatted or else they will appear broken.

The change has been rolled out slowly in part to let brands, agencies, page management companies and other marketers finish running campaigns that relied on the wider tab size. While Facebook likes to move fast, the change would have broken a key interface used by its increasingly large advertising client base.