Aspect Ratio Calculator

Resize without distorting

Changing just one dimension of an image or a video means you also have to change the other by exactly the same proportion, or the result comes out stretched and distorted. This calculator works out aspect ratios and resizes dimensions proportionally for you, so you can find the correct height for a given width, or check that a set of new dimensions still keeps the original shape intact. It removes the small but easy-to-get-wrong arithmetic that causes squashed images.

Why the ratio is the thing to preserve

An aspect ratio is simply the fixed relationship between width and height, and keeping it constant when you resize is exactly what prevents distortion. Common ratios recur everywhere for good reasons, 16:9 for video, 4:3 for older screens, 1:1 for square social posts, 3:2 for photographs, because devices and platforms have standardised on them. Given any three of the four quantities, width, height, and the two parts of the ratio, the fourth follows automatically, which is precisely the arithmetic this tool does for you instantly.

Common ratios built in

It runs entirely in your browser, so nothing you enter is uploaded and the generated code is yours to paste straight into a project. Because it works client-side, you can iterate freely, regenerating as often as you like without a round trip to any server.

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