Aspect Ratio Calculator
Calculate aspect ratios from dimensions, simplify ratios, and find missing width or height. Includes common presets like 16:9, 4:3, and 21:9.
Find Aspect Ratio
16:9
Decimal: 1.7778
Calculate Missing Dimension
1080 px
1920 x 1080 px (16:9)
Common Resolutions
How It Works
This calculator helps you work with aspect ratios in two ways:
- Find Ratio: Enter any width and height to get the simplified aspect ratio. The tool finds the greatest common divisor (GCD) to reduce the ratio to its simplest form (e.g., 1920×1080 → 16:9).
- Calculate Dimension: Select or enter an aspect ratio, provide one known dimension (width or height), and the calculator will compute the missing dimension while maintaining the correct proportions.
Common ratio presets are provided for quick access. The calculator updates instantly as you type.
Frequently Asked Questions
What is an aspect ratio?
An aspect ratio is the proportional relationship between the width and height of an image or screen, expressed as two numbers separated by a colon (e.g., 16:9). It describes the shape of the display, not the actual size.
What is the most common aspect ratio for monitors?
16:9 is the most common aspect ratio for modern monitors, TVs, and laptop screens. Common resolutions in this ratio include 1920x1080 (Full HD), 2560x1440 (QHD), and 3840x2160 (4K UHD).
How do I calculate a missing dimension from an aspect ratio?
If you know the aspect ratio (e.g., 16:9) and one dimension (e.g., width = 1920), divide the known dimension by its ratio component and multiply by the other: height = (1920 / 16) × 9 = 1080.
What aspect ratio should I use for social media?
1:1 (square) works for Instagram feed posts, 9:16 (vertical) for Stories and Reels, 16:9 (landscape) for YouTube, and 4:5 for Facebook and Instagram portrait posts.