Aspect Ratio Calculator

How the second side is calculated

The height equals the width multiplied by the second number of the ratio and divided by the first. With 16:9 and a width of 1920 the result is exactly 1080. At a width of 1000 the exact height is 562.5, and half a pixel does not exist: the calculator rounds it to 563 and shows how far the ratio has moved from 16:9. For 16:9, sizes come out even whenever the width is divisible by 16.

The "21:9" label on monitors

Exactly 21:9 is, for example, 2520 × 1080. Monitors labeled 21:9 usually have a resolution of 2560 × 1080 (exactly 64:27) or 3440 × 1440 (43:18), so a calculation from a width of 2560 gives a height of 1097 instead of 1080. The resolution table marks this, and clicking such a row switches the calculator to that monitor's actual ratio.

Scale

Both sides are multiplied by the percentage and rounded to whole pixels. If rounding shifts the ratio, the exact value appears under the size. To read the aspect ratio of a finished image from the file itself, use Image Aspect Ratio Finder.