Text in Facebook add should not cover more than 20% of the image.

You can check the percentage of text in your creative by using this grid tool

It's considered one box as long as the box covers one part of the word, so please make sure the text is placed within 5 boxes.

The 20% text policy doesn't include
• Pictures of products that include text on the actual product

  (ex: book covers, album covers, movie posters).
• Embedded text on images of games and apps.
• Cartoons where text is part of the cartoon.

The 20% text policy does include:
• Logos and slogans.
• Images with text overlay (ex: watermarks).
• Images that are clearly edited to include text on the product as a loophole to policy.

Hard to find, so I made it myself to share it with the community.