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

The 4:5 aspect ratio is generally recommended for mobile video ads on Reddit because it effectively utilizes the vertical screen space of mobile devices without being fully portrait. This ratio allows the video to appear larger and more engaging in the user's feed compared to wider formats like 16:9, which would appear smaller with letterboxing. While 9:16 is a full portrait format, 4:5 offers a good balance, providing significant screen presence while still being adaptable for various mobile viewing experiences and often performing well in terms of engagement. 3:2 is less common and would not fill the mobile screen as effectively as 4:5.