Aspect Ratio Calculator

Aspect ratio is the proportional relationship between width and height, expressed as two numbers separated by a colon — like 16:9 (widescreen) or 4:3 (classic TV). It determines the shape of images, videos, and display screens.

Common aspect ratios include 16:9 (YouTube, most monitors), 9:16 (Instagram Stories, TikTok), 1:1 (Instagram posts), 4:5 (Instagram portrait), and 21:9 (ultrawide cinema). Knowing the ratio lets you resize content proportionally without distortion — changing one dimension automatically determines the other.

This tool calculates the missing dimension when you know the ratio and one side, finds the ratio from any width/height pair, and includes presets for all major social media and video platforms. Essential for designers preparing assets across multiple screen sizes and platforms.