Which video aspect ratio is commonly used in Facebook video feeds?

The aspect ratio of 4:5 is particularly suitable for Facebook video feeds because it effectively utilizes the available screen space on mobile devices, which are the primary platform for Facebook users. This aspect ratio is optimized for vertical viewing, allowing videos to capture more of the viewer's attention as they scroll through their feeds. It strikes a balance between height and width that engages users without the video being too tall or too wide, making it a visually appealing choice in a platform that prioritizes user experience.

In contrast, while other aspect ratios like 9:16 (which is vertical) might be great for Stories or Reels, they may not work as well for standard feeds. The 1.91:1 ratio, often used for landscape videos, may be less engaging in the vertical scrolling context of Facebook's feed. Lastly, 16:9, although standard in many video formats, does not translate effectively for mobile-first viewing on social media. The 4:5 ratio aligns well with Facebook's design and user engagement strategies, making it the optimal choice for video content in news feeds.