What is aspect ratio?
The proportional relationship between a video or image's width and height, written as two numbers like 9:16 or 16:9.
Aspect ratio describes shape, not size - a 9:16 video is "tall" whether it's 1080×1920 or 540×960. Every short-form platform is built around one primary shape: 9:16 for TikTok, Reels and Shorts; 16:9 for widescreen; 1:1 or 4:5 for feed posts.
Posting the wrong ratio doesn't just look odd - most platforms crop or letterbox it, cutting off the left and right sides of a landscape video cropped to fill a vertical feed, or adding bars around a square video in a widescreen player.
Koldflux picks the right codec, container and bitrate for every platform automatically - this glossary exists because our own team had to get it right first.
Automate this in Koldflux