This is going to be a very quick post with an information link below that while short and sweet, can help. Creating a social media banner is not hard, yet there and MANY examples of badly cropped or fuzzy banners.
Facebook for example clearly states that its banner needs to be 851 x 351 pixels. There are many editing programs that will allow one to create a banner in this size, and this works out to about 8.8 inches x 3.6 inches for standard 96 dpi web graphics. With the exception of retinal display monitors, there is little benefit to creating a banner greater than 96 dpi. If your banner is larger than these dimensions, Facebook will crop it in some pretty strange ways. If your resolution is much higher or lower than 96 dpi, the image may look fuzzy. Try to say something about yourself, and be creative so that your page will stand out.
While there is something to be said for occasionally changing your banner, if you are a professional changing your banner too often may confuse those who may want to use your services. Professionals often develop a brand that has a certain look relating to colors, shapes and overall design. Repeat customers may pay a return visit to your social media page and believe that they have hit the wrong page if your banner is frequently different.
Twitter is a little bit more generous with its header. You are allowed a header of 1500 x 500 pixels (about 15.6 x 5.2 inches) which would lend itself to a panoramic type image. Once again thing about producing a header with harmonious colors, one or two fonts at the most. On line applications such as www.PicMonkey. com allow you to enter the dimensions of your header directly into fields so that there is no guessing involved with your creation.
For those who enjoy videos on Youtube, Youtube has a template that you can directly download. The size is 1546 x 423 pixels ( about 16 inches x 4.4 inches at 96 dpi). Once again you can use an on line application like PicMonkey to design your header or banner.
For those who would like a little more creative control and enjoy Photoshop, Phlearn has produced a video with downloadable templates for each of these social media sites.