What aspect ratio is generally recommended for mobile video ads on Reddit?

The 4:5 aspect ratio is recommended for mobile video ads on Reddit because it optimizes for vertical viewing, which is how most users hold their phones. This ratio allows the video to take up more screen real estate without being cut off, increasing visibility and engagement. While 9:16 is also vertical, it's often too tall and can be cropped or require users to rotate their device, which is less ideal. 16:9 is a horizontal (landscape) ratio, which is not optimal for mobile viewing as it appears much smaller on a vertical screen. 3:2 is a less common ratio and would not fill the screen as effectively as 4:5.