Aspect Ratio Tool

What an aspect ratio is and how the calculator helps

An aspect ratio is the relationship between an image's width and height, written as two numbers separated by a colon, like 16:9 or 4:3. It decides how a graphic, photo or video fits on a screen or page. Export something in the wrong ratio and it ends up cropped, letterboxed or stretched.

Working out ratios by hand is slow, and mistakes creep in with unusual dimensions or when you move between formats. This free aspect ratio calculator finds the ratio of any dimensions and fills in a missing width or height without changing the proportions. Say you have an image 1920 pixels wide and want it in 4:3. Enter the width, choose 4:3, and the calculator shows a height of 1440 pixels.

Different kinds of content have settled on different ratios. TV and online video, YouTube included, use 16:9, while square Instagram posts use 1:1. Photographers usually shoot in 3:2 because that is what most DSLR cameras produce, and filmmakers pick 21:9 for a wide cinematic frame. Phones made 9:16 vertical video the norm on TikTok and Instagram Stories. The calculator handles all of these, plus any custom size.

To turn a 1080p video (1920x1080) into a square, enter those dimensions and choose 1:1 to get 1080x1080. If you want to know the ratio of a resolution like 2560x1440, enter it and the calculator reduces it to 16:9.

Enter a width and height, or pick one of the preset ratios. The calculator reduces the ratio to its simplest form, shows its decimal value and common name, and gives you the missing dimensions, whether the file is going to print, a website or a video edit.