Aspect Ratio Calculator — Screen & Image
Calculate and convert between aspect ratios. Find missing dimensions for any screen or image.
What Is the Aspect Ratio Calculator — Screen & Image?
The Aspect Ratio Calculator finds the simplified ratio of width to height for any dimensions, and computes new dimensions when resizing while maintaining the original ratio. Used by designers, video editors, photographers, and web developers to resize images and videos without distortion.
Formula
How to Use
Enter the original width and height. The tool immediately shows the simplified aspect ratio (e.g., 16:9). To find new dimensions at a different size, enter either the new width or new height and the other dimension is calculated automatically to preserve the ratio.
Example Calculation
Original: 1920 × 1080 → GCD(1920,1080) = 120 → Ratio = 16:9. To resize to width 1280: New Height = 1280 × (1080/1920) = 720. Result: 1280 × 720, which is still 16:9.
Understanding Aspect Ratio — Screen & Image
Aspect ratio defines the proportional relationship between width and height in any rectangular image, video, or screen. Maintaining the correct aspect ratio is critical when resizing media — scaling width and height independently causes stretching or squashing that degrades visual quality.
Common aspect ratios include 16:9 for widescreen video and HD displays, 4:3 for classic TV and photography, 1:1 for square social media posts, and 21:9 for ultra-wide cinema content. The calculator reduces any width/height pair to its simplest ratio using the greatest common divisor algorithm.
This tool is particularly useful in responsive web design, where you need to scale an element proportionally across breakpoints, and in video production, where source footage must match platform export specifications. Enter your original dimensions once and calculate all target sizes in seconds.
Frequently Asked Questions
What is a 16:9 aspect ratio?
16:9 is the standard widescreen aspect ratio used by HD televisions, YouTube videos, and most modern monitors. For every 16 units of width there are 9 units of height.
What aspect ratio is used for smartphones?
Modern smartphones commonly use 9:16 (portrait) or 18:9 / 19.5:9 for ultra-wide screens. Social media stories use 9:16.
What is 4:3 used for?
4:3 was the standard TV and monitor ratio before widescreen. It is still used in some digital cameras, older displays, and certain social media formats.
How is the GCD used in aspect ratios?
The Greatest Common Divisor (GCD) of width and height is used to reduce both numbers to their simplest form. For 1920×1080, GCD=120, giving 1920/120 : 1080/120 = 16:9.
Is this calculator free?
Yes, completely free with no registration required.
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