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Aspect Ratio Calculator

Calculate aspect ratios for images and videos. Enter width or height with a ratio (16:9, 4:3, 1:1) to find the other dimension.

Select Aspect Ratio

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Dimensions

Actual ratio: 16:9 (1.7778:1)
Quick fill:

Preview

16:9
1920 x 1080
CSS
aspect-ratio: 16 / 9;
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Frequently Asked Questions

What is an aspect ratio?
An aspect ratio is the proportional relationship between width and height. It is expressed as two numbers separated by a colon, like 16:9 or 4:3. A 16:9 ratio means for every 16 units of width, there are 9 units of height. Aspect ratios are used in displays, photography, video production, and web design to maintain consistent proportions.
What is the most common aspect ratio?
16:9 (widescreen) is the most common aspect ratio for modern displays, TVs, YouTube videos, and streaming content. Other common ratios include 4:3 (classic TV/monitors), 1:1 (square, Instagram posts), 21:9 (ultrawide cinema), and 9:16 (vertical video, TikTok/Instagram Stories).
How do I use the CSS aspect-ratio property?
The CSS aspect-ratio property sets the preferred aspect ratio for an element. Use it like: aspect-ratio: 16 / 9; This tells the browser to maintain a 16:9 proportion. Combined with width: 100%, the height adjusts automatically. It is supported in all modern browsers and is the cleanest way to create responsive aspect-ratio containers.
How do I calculate dimensions from an aspect ratio?
To find the height from a width and ratio: height = width * (ratio_height / ratio_width). For example, for a 1920px wide 16:9 video: height = 1920 * (9/16) = 1080px. To find the width from a height: width = height * (ratio_width / ratio_height). For a 1080px tall 16:9 video: width = 1080 * (16/9) = 1920px.
What aspect ratio should I use for social media?
Each platform has preferred ratios: Instagram feed posts use 1:1 (square) or 4:5 (portrait). Instagram/TikTok Stories use 9:16 (vertical). YouTube videos use 16:9. Twitter/X images work best at 16:9 or 2:1. Facebook posts typically use 1.91:1. Using the correct ratio prevents cropping and ensures your content looks professional.
Can I use custom aspect ratios?
Yes, this calculator supports any custom ratio. Enter your desired width and height ratio values, and the tool will calculate dimensions accordingly. Custom ratios are useful for specific design requirements, print layouts, or matching non-standard display sizes.

How to Use the Aspect Ratio Calculator

Whether you are sizing images for a website, setting up video exports, or designing responsive containers, our aspect ratio calculator helps you find the exact dimensions you need while maintaining perfect proportions.

Step 1: Select an aspect ratio. Choose from common presets like 16:9 (widescreen), 4:3 (standard), 1:1 (square), 21:9 (ultrawide), or enter a custom ratio. The calculator supports any ratio values you need.

Step 2: Enter a dimension. Type either a width or height value in pixels. The other dimension is calculated automatically based on the selected aspect ratio. Change either value and the other updates in real-time.

Step 3: Copy the CSS. The tool generates the CSS aspect-ratio property value ready to paste into your stylesheet. This modern CSS property is the cleanest way to create responsive containers that maintain their proportions at any size.

Understanding Aspect Ratios in Web Design

Aspect ratios are fundamental to responsive web design. When images and videos need to scale fluidly across screen sizes, maintaining the correct aspect ratio prevents stretching, squishing, or unwanted cropping. The CSS aspect-ratio property (supported in all modern browsers since 2021) provides a native way to enforce proportional sizing without padding hacks.

Before the aspect-ratio property, developers used the "padding-top percentage trick" where a container with padding-top: 56.25% (which is 9/16 * 100) would create a 16:9 container. While this technique still works, the aspect-ratio property is cleaner, more semantic, and works with both width and height constraints. It also integrates naturally with CSS Grid and Flexbox layouts.

Common Aspect Ratios and Their Uses

16:9 (1.78:1) - Widescreen. The standard for HD and 4K content. Used by YouTube, most streaming platforms, and virtually all modern monitors and TVs. Common resolutions: 1920x1080 (Full HD), 2560x1440 (QHD), 3840x2160 (4K UHD).

4:3 (1.33:1) - Standard. The classic TV and early computer monitor ratio. Still used for presentations (PowerPoint defaults to 4:3), some tablets (iPad), and certain photography compositions. Common resolutions: 1024x768, 1600x1200.

1:1 - Square. Instagram popularized the square format for social media. Used for profile pictures, thumbnails, and album artwork. The equal proportions create a balanced, symmetrical frame suitable for centered subjects.

9:16 (0.56:1) - Vertical. The vertical video format used by TikTok, Instagram Stories, and YouTube Shorts. As mobile-first content dominates, this ratio has become essential for social media marketing and content creation.

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