If you're planning to advertise (or promote) your Facebook posts, there are additional restrictions you need to follow to keep Facebook from rejecting your ads. The biggest of these is the 20% text restriction. Although this limit is listed in Facebook's requirements, they don't explain how they calculate it. To calculate the text percentage, Facebook draws a 5x5 grid over the portion of the ad visible in the timeline view. If text covers any portion of a square, the whole square is counted. If your text covers more than 5 squares, your ad will likely be rejected.