Have you ever wondered what size photo you should use for your Facebook Cover Page or your Profile Picture?
Cover photos should be 851 pixels wide and 315 pixels tall. If you upload an image that’s smaller than these dimensions, it will be stretched to this larger size. The image you upload must be at least 399 pixels wide and 150 pixels tall.
Also, for images with your logo or text, you may get a higher quality result by using a PNG file.