Aspect Ratio Calculator

Aspect ratios shape how we experience visual media across film, photography, and screens. Understanding them helps you choose the right dimensions for any project.

Film & Television

The 16:9 ratio is the global standard for HDTV, streaming, and online video. It replaced 4:3 in the late 1990s and is used by YouTube, Netflix, and broadcast television. 21:9 (2.35:1) is the cinematic widescreen format used in movie theaters, providing an immersive, panoramic view. Classic films were shot in 4:3 (1.33:1) before widescreen became popular.

Photography & Mobile

Standard DSLR and mirrorless cameras capture in 3:2, the same ratio as 35mm film. Micro four-thirds systems use 4:3. For social media, 1:1 (square) is ideal for Instagram posts, while 9:16 dominates vertical video on TikTok, Instagram Reels, and YouTube Shorts. 2:1 is gaining popularity for mobile-first wide content.

How the Math Works

To simplify an aspect ratio, you divide both dimensions by their greatest common divisor (GCD). The GCD of two numbers is the largest number that divides both of them without a remainder. For example:

When finding missing dimensions, the calculator uses cross-multiplication. If your ratio is W:H and you know the width, the height is calculated as (width × H) ÷ W. This ensures your resized image or video maintains its original proportions without stretching or distortion.

Frequently Asked Questions

Related Tools