Aspect Ratio Calculator

An aspect ratio is the proportional relationship between a frame's width and height — for example 16:9 (widescreen) or 9:16 (vertical). It determines the shape of your video regardless of its pixel size.

Multiply the width by the ratio's height and divide by its width. For 16:9 at 1920px wide: 1920 × 9 ÷ 16 = 1080px tall. This calculator does that for you — pick a ratio, lock one dimension, and read off the other.

Use 16:9 for YouTube and desktop, 9:16 for Reels, Shorts, Stories, and TikTok, 1:1 for square feed posts, and 4:5 for portrait feed posts. See our Social Video Size Guide for exact pixel sizes per platform.

Yes — it's completely free, runs entirely in your browser, and requires no sign-up.