Aspect ratios for web and social images
What aspect ratio means, the common ratios for avatars, thumbnails and stories, and how to crop instead of stretch so images stay sharp.
What an aspect ratio actually is
An aspect ratio is the relationship between an image's width and its height, written as two numbers such as 1:1, 4:3 or 16:9. A 1:1 image is a perfect square, while 16:9 is a wide landscape shape roughly one and three quarter times as wide as it is tall. The ratio describes shape, not size, so a 1:1 crop looks the same whether it ends up 200 by 200 or 2000 by 2000 pixels. Choosing the right ratio before you crop stops a platform from adding its own crop or letterbox bars later.
Common ratios and where they are used
Square 1:1 crops suit profile pictures, avatars and grid thumbnails because they display the same at any size. Landscape 16:9 is the standard for video thumbnails and slide decks, and 4:3 and 3:2 match many camera photos. Portrait ratios flip these: 9:16 fills a phone screen for stories and short video, and 2:3 is a classic tall photo shape. Picking the ratio your destination expects means the whole crop is shown instead of the edges being trimmed off automatically.
Cropping versus resizing versus stretching
Cropping removes pixels from the edges to change the shape, keeping the remaining pixels exactly as they were. Resizing scales the whole image up or down, which can soften detail when enlarging. Stretching forces an image into a new ratio without removing anything, which distorts faces and shapes and should be avoided. When you need a new shape, crop to it rather than stretch, and this tool always crops so nothing is squashed. If the result is then too large, resize the crop afterward.
Choosing a crop that keeps the subject
A locked ratio fixes the shape but you still choose what falls inside it. Reposition the box so the main subject sits near the center or on a natural line, and leave a little breathing room at the edges. For faces, keep the eyes in the upper third and avoid cutting through the chin or top of the head. The live pixel readout helps you land on round numbers when a platform asks for a specific minimum size.