On the mobile app, posts are displayed in a 1:1 aspect ratio. That means that the width of the post is the same as the height of the post. The aspect ratio of a post is important because it determines how much of the post is visible on different devices. Instagram supports three sizes for image posts. 1: The most basic post i.e. square image post- 1080*1080 px. 2: For landscape images - 1080*566 px. 3: Portrait images - 1080*1350 px.