It is, however, recommended to upload it in larger dimensions, to get a better quality photo when you tap to view the full photo. The dimensions of your profile photo should be at least 360x360px.
However, if you upload pictures with different ratios, spacing will be added around them when you view them in theatre mode. You can also use photos with a square image ratio (1200x1200px recommended), or the 4:5 ratio (960x1200px), and it will look just as good. When uploading regular images with your statuses, Facebook recommends using ones whose size is 1200x900px, especially if you’re going to sponsor those posts. Basically, nothing bad will happen if you stray from their image size and type guidelines, but if you want to get the most out of your images, try to get them all to follow the same size/type chart. It has sure been a bumpy ride so far – Facebook changes its layout quite a lot, which also comes with changes in recommended image sizes. That is why we decided to create an updated guide for the most commonly used image sizes. They have redesigned the News Feed, Timeline and Pages several times, and also introduced a couple of new types of Facebook ads. Facebook’s design is constantly being upgraded.