What are the dimensions for my Page’s cover photo, profile picture and app thumbnails?
Page cover photos are 851 pixels wide and 315 pixels tall. if you upload an image smaller than that it will be stretched. Minimum file size is 399 x 150 px. A PNG file will give higher quality and a JPG will get faster loading time.
Page profile pictures are displayed at 160 x 160 px but the photo you upload must be at least 180 x 180 px. We would recommend that you upload an PNG file which will give you a high quality image. This is extra important when it comes to graphic images such as logos etc. This image will also be shown around Facebook representing your page.
App thumbnail images are 111 x 74 pixels. File size limit 5MB.