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Aspect Ratio Calculator

Calculate aspect ratios, convert dimensions, and find the right size for any platform.

Enter Dimensions

Type width and height to get the simplified aspect ratio.

Aspect Ratio

16:9

Decimal: 1.7778

Quick Presets

Click a preset to fill in common aspect ratios.

Visual Preview

Proportional representation of the current aspect ratio.

16:91920 x 1080

Platform Reference

Common aspect ratios and sizes for popular platforms.

PlatformFormatRatioPixels
YouTubeVideo16:91920x1080
InstagramFeed Post1:11080x1080
InstagramStory9:161080x1920
InstagramPortrait4:51080x1350
TikTokVideo9:161080x1920
FacebookCover~2.63:1820x312
TwitterHeader~3:11500x500
LinkedInBanner~4:11584x396

What Is an Aspect Ratio

An aspect ratio is the proportional relationship between the width and height of an image, video, or screen. It is expressed as two numbers separated by a colon, such as 16:9, where the first number represents width and the second represents height. Aspect ratios matter because they determine how content fits on different screens and platforms.

This calculator simplifies any width and height pair into its lowest-term ratio using the greatest common divisor (GCD) algorithm. For example, 1920x1080 simplifies to 16:9 because both numbers share a GCD of 120. The tool runs entirely in your browser with no data sent to any server.

Social Media Dimensions Guide

Every social media platform has preferred image and video dimensions. Using the wrong size causes your content to be cropped, stretched, or displayed with black bars, reducing engagement and visual quality.

Instagram uses 1:1 (1080x1080) for feed posts, 4:5 (1080x1350) for portrait posts that take up more screen space, and 9:16 (1080x1920) for Stories and Reels. TikTok also uses 9:16 for its full-screen vertical video format. YouTube uses 16:9 (1920x1080) as its standard. Facebook cover photos use a wide 820x312 format, while LinkedIn banners stretch even wider at 1584x396.

Use the platform reference table in this tool to quickly look up the correct dimensions for any platform before creating your content.

Video Aspect Ratios Explained

The most common video aspect ratio is 16:9, which has been the standard for HD and 4K content since the transition from CRT to widescreen displays. Common resolutions in 16:9 include 1280x720 (720p), 1920x1080 (1080p), 2560x1440 (1440p), and 3840x2160 (4K).

Vertical video at 9:16 has become equally important with the rise of mobile-first platforms like TikTok, Instagram Reels, and YouTube Shorts. Ultrawide content uses 21:9 for cinematic presentations and gaming. The older 4:3 ratio is still found in legacy content and some presentation formats.

When repurposing content across platforms, you often need to convert between these ratios. This calculator helps you determine the exact pixel dimensions needed when changing aspect ratios while keeping one dimension fixed.

Responsive Design and Aspect Ratios

In web development, maintaining consistent aspect ratios prevents layout shifts as images and videos load. CSS provides the aspect-ratio property that lets you set a preferred ratio for any element. For example, aspect-ratio: 16/9 ensures a video container maintains its proportions regardless of viewport width.

When building responsive layouts, knowing the exact ratio of your media helps you reserve the correct amount of vertical space. This prevents content from jumping around as assets load, which improves both user experience and Core Web Vitals scores. Use this calculator to determine the ratio of any image or video, then apply that ratio in your CSS for stable, predictable layouts.

Frequently Asked Questions

How do I calculate an aspect ratio from pixel dimensions?

Divide both the width and height by their greatest common divisor (GCD). For example, 1920 and 1080 share a GCD of 120. Dividing both by 120 gives you 16 and 9, so the aspect ratio is 16:9. This calculator performs that math automatically as you type your dimensions.

What is the best aspect ratio for social media?

It depends on the platform and format. Instagram feed posts work best at 1:1 (square) or 4:5 (portrait). Stories and Reels use 9:16 (vertical). YouTube videos are 16:9 (landscape). TikTok uses 9:16. Check the platform reference table in this tool for the full list of recommended sizes and ratios.

How do I convert between aspect ratios?

Use the Calculate Dimension mode in this tool. Enter your target aspect ratio (for example, 9:16) and one known dimension (for example, width of 1080). The calculator will compute the other dimension automatically. In this case it would return a height of 1920 pixels.

What is the difference between 16:9 and 4:3?

A 16:9 ratio is wider and shorter, used for modern HD and 4K displays. A 4:3 ratio is more square-shaped, dating back to standard definition television and older computer monitors. At the same width, a 4:3 image is 33% taller than a 16:9 image. Most modern content is produced in 16:9, but 4:3 still appears in some presentation software and legacy media.

Does this tool store my data?

No. All calculations happen locally in your browser using JavaScript. No dimensions, ratios, or any other data are sent to a server. Closing the tab clears everything. There are no accounts, logs, or data collection of any kind.

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