Aspect Ratio Calculator
Calculate, convert, and resize aspect ratios for images, videos, and screens. All processing happens in your browser.
Select a ratio preset or enter a custom ratio, then provide one dimension to calculate the other.
Common screen, video, and social media resolutions with their aspect ratios. Click "Use" to load a resolution into the calculator.
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About Aspect Ratios
An aspect ratio describes the proportional relationship between the width and height of an image, video, or screen. Expressed as two numbers separated by a colon (such as 16:9), it tells you how many units wide an image is for every unit of height. Understanding aspect ratios is essential for anyone working with visual media, whether you are designing websites, editing video, preparing social media graphics, or choosing a monitor.
The most common aspect ratio in modern media is 16:9, which became the international standard for high-definition television and is used by virtually all computer monitors, laptops, and smartphones in landscape orientation. Before widescreen became standard, 4:3 was the dominant ratio for television and early computer monitors. Today, ultra-wide displays use 21:9 for an immersive cinematic experience, while mobile-first content creators frequently work in 9:16 for vertical video on platforms like TikTok, Instagram Reels, and YouTube Shorts.
Aspect Ratios in Web Design
Web designers must consider aspect ratios when creating responsive layouts. Images that are embedded without explicit dimensions can cause layout shifts as they load, hurting Core Web Vitals scores. By specifying width and height attributes in HTML or using the CSS aspect-ratio property, designers can reserve the correct space before images load. This prevents content from jumping around, improving both user experience and search engine rankings. Common choices for hero images include 16:9 and 2:1, while thumbnails often use 4:3 or 1:1 squares for grid layouts.
Aspect Ratios for Social Media
Each social media platform has preferred aspect ratios for different content types. Instagram supports 1:1 (square), 4:5 (portrait), and 1.91:1 (landscape) for feed posts. Facebook and LinkedIn share links use 1.91:1 for preview images. Twitter cards work best with 2:1 or 1:1. YouTube thumbnails are 16:9. Pinterest favors 2:3 vertical pins. Using the correct ratio prevents cropping and ensures your content displays as intended across all platforms. This calculator helps you quickly convert between these formats.
FAQ
Q: What is the most common aspect ratio for videos?
A: The most common video aspect ratio is 16:9, used for Full HD (1920x1080), 4K UHD (3840x2160), and most YouTube content. For vertical videos on TikTok and Instagram Reels, 9:16 is standard. Cinema typically uses wider ratios like 2.39:1 or 21:9.
Q: How do I calculate aspect ratio from pixel dimensions?
A: Divide both the width and height by their greatest common divisor (GCD). For example, 1920x1080: the GCD of 1920 and 1080 is 120, so 1920/120 = 16 and 1080/120 = 9, giving you 16:9. This calculator does this automatically.
Q: What aspect ratio should I use for Instagram?
A: Instagram supports several ratios: 1:1 (1080x1080) for square posts, 4:5 (1080x1350) for portrait posts (recommended for maximum feed real estate), and 1.91:1 (1080x566) for landscape. Stories and Reels use 9:16 (1080x1920).
Q: What is the difference between 2K and 4K resolution?
A: 2K (QHD) is 2560x1440 pixels, while 4K (UHD) is 3840x2160 pixels. Both use a 16:9 aspect ratio. 4K has exactly four times the pixel count of Full HD (1920x1080), making it ideal for large displays and detailed content.
Q: Is my data safe when using this tool?
A: Yes. This tool runs entirely in your browser using JavaScript. No data is sent to any server. All calculations happen locally on your device. You can verify this by checking your browser's network tab while using the tool.