Aspect ratio is the relationship between an image’s width and height, written as width:height. It is independent of resolution — 1280×720 and 1920×1080 are both 16:9.
Common ratios
- 16:9 — video, presentation slides, most screens, YouTube thumbnails.
- 4:3 — older cameras and displays, some print layouts, tablets.
- 1:1 — profile pictures, product tiles, feed posts on square-first platforms.
- 3:2 — the classic 35 mm photo ratio, common in DSLRs and prints.
- 9:16 — vertical video and stories: phone-screen shaped.
Working it out
If you know the ratio and one dimension, the Aspect Ratio Calculator gives you the other. It can also reduce a pixel size like 1920×1280 to its simplest ratio (3:2), which is handy for checking whether two images match.
Changing ratio
You cannot change a ratio without either cropping or adding space. To go from 4:3 to 16:9, crop the top and bottom with the Image Cropper, or add bars with Add Image Border. Never stretch — it distorts everything in the frame.
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