Video Aspect Ratio & Resolution Calculator

About Video Aspect Ratio & Resolution Calculator

The AT USE Video Aspect Ratio Calculator is a small but indispensable utility for anyone who works with video at multiple destinations. Set any two of {width, height, aspect ratio} and the calculator instantly fills in the third with the correct integer pixel value, snapping to even numbers when needed (most encoders require even dimensions). Use the preset chips to switch between the most common destinations: 16:9 for YouTube and standard widescreen, 9:16 for YouTube Shorts / Instagram Reels / TikTok, 1:1 for Instagram square posts, 4:5 for Instagram portrait, 2:3 for Pinterest, and 21:9 for ultrawide cinematic exports. There is no login, no account, and no math — just type a number and the rest updates live. Editors use it before exporting; social media managers use it when planning reformats across platforms; and developers use it when sizing video components in HTML and CSS.

Common use cases

• Compute the height to use when exporting at 1920px wide and 16:9.
• Convert a 4K master into a 9:16 Shorts/Reels canvas without distortion.
• Pick the right square (1:1) or portrait (4:5) crop for Instagram.
• Plan ultrawide 21:9 cinematic exports from 16:9 source footage.
• Find the dimensions that fit a 1080-tall mobile screen exactly.

How to use it

1. Click a preset chip (16:9, 9:16, 1:1, 4:5, 21:9) or type a custom ratio.
2. Enter either the target width or the target height.
3. Read the computed value, snapped to a codec-safe even number.
4. Use it to plan exports, crops, or resizes across platforms.

Frequently asked questions