Aspect Ratio Calculator

An aspect ratio describes the relationship between width and height. A 1920 by 1080 image and a 1280 by 720 image are both 16:9. When the ratio stays the same, circles remain round and faces do not look stretched.

The calculator multiplies the new width by the original height, then divides by the original width. It rounds the result to a whole pixel because image and video dimensions normally use whole numbers.

Common ratios

16:9 is common for video and wide screens. 4:3 appears in older displays and some presentation layouts. 1:1 is square. 3:2 is common in photography, while 9:16 is a vertical phone-video format. The ratio alone does not determine image quality; the final pixel dimensions do.

Before resizing

Enter the actual source dimensions, then choose either the desired width or height. If another platform requires both exact dimensions and a different ratio, crop the image instead of forcing it to stretch. Keep a copy of the original so you can create another size later.