Hat tip to Mari Smith over at marismith.com for alerting us to the very useful Facebook cover compliance tool.
What is the Facebook 20% cover rule?
All covers are public. This means that anyone who visits your Page will be able to see your cover. Covers can’t be deceptive, misleading, or infringe on anyone else’s copyright. You may not encourage people to upload your cover to their personal timelines. Covers may not include images with more than 20% text.