You already knew that only 20% of your Facebook Page’s Cover Photo can be occupied with text as of a policy change that was announced in December and went into effect in January. But did you know the rule applies to images used in Ads and Sponsored Stories in the News Feed?

We have the official policy document from Facebook embedded right here for your reference. It was emailed from Facebook to Craig Glaser, a marketing analyst at Advomas and one of Sprout Social‘s valued customers, after one of his promoted posts was denied. He thought it would be useful to Sprout Insights readers, and we agree.

It might sound easy enough to say that text can’t fill more than 20% of your image, but for graphic and web designers, it turns out there’s a lot of grey area and uncertainty in that simple statement, so this document goes into great detail about where the line is in various circumstances.

Whether you’re working with a separate design team or your social managers are producing graphics themselves for promotion, this is a handy resource. Take a look below, or read it directly on Scribd.