Aspect ratio
The shape of a photo or video, written as width to height, such as 1:1 for square or 9:16 for tall vertical video.
Each network shows media in a few set shapes, and anything else gets cropped or letterboxed. Instagram feed posts look best at 4:5 portrait, Stories, Reels, TikTok and Shorts use 9:16, YouTube videos and thumbnails use 16:9, and Pinterest favours 2:3 pins.
Picking the ratio before you post means you choose what's in the frame, not the app. It also decides how much of the screen a post fills: a 4:5 photo takes up noticeably more of a phone feed than a 1.91:1 landscape one.
Example
A 1080 × 1350 photo is 4:5; a 1920 × 1080 video is 16:9.
Free Instagram photo resizer →
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