How do I calculate the aspect ratio of an image?

Divide the width and height by their greatest common divisor. For example, 1920 and 1080 both divide by 120, giving 16 and 9 — so the aspect ratio is 16:9.

How do I calculate an aspect ratio from pixels?

Divide both the width and the height by their greatest common divisor. For example, 1920 by 1080 divided by 120 gives 16 by 9, so the aspect ratio is 16:9. This calculator does that simplification for you instantly.

What are the dimensions for 16:9?

Common 16:9 dimensions include 1280 by 720 (HD), 1920 by 1080 (Full HD), 2560 by 1440 (QHD) and 3840 by 2160 (4K UHD). Any pair where width divided by height equals 1.78 is 16:9.

Why does keeping the aspect ratio matter when resizing?

If you change width and height by different amounts, the image stretches or squashes and people and objects look distorted. Resizing in proportion keeps everything looking natural.

What aspect ratio should I use for social media?

It depends on the placement: 1:1 for square feed posts, 4:5 for portrait feed posts, 9:16 for stories, reels and shorts, and 16:9 for YouTube videos and landscape posts.

CALCULATORS · FREE ONLINE TOOL

Aspect Ratio Calculator

Work out any aspect ratio and resize dimensions without distortionYou resize an image for a thumbnail, type in 1280 by 720, and it comes out stretched with faces too wide. The problem was never the size, it was the ratio. This calculator reduces any dimensions to their simplest ratio and scales without distortion.

✓ Free to use✓ No sign-up✓ Ready in your browser

// ASPECT RATIO CALCULATOR · GET STARTED

Use Aspect Ratio Calculator

Work out any aspect ratio and resize dimensions without distortion

Find the ratio of a size

Width (px)

Height (px)

Aspect ratio: 16:9 (1.778 : 1)

Resize while keeping a ratio

Ratio width

Ratio height

New width (px)

New height (px)

Type a new width or height and the other side is calculated from the ratio, so your image or video never stretches.

// ASPECT RATIO CALCULATOR · AT A GLANCE

Aspect Ratio Calculator: what to know first.

Work out any aspect ratio and resize dimensions without distortion

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Aspect ratios show up everywhere: video exports, image uploads, screen sizes, print layouts and social media crops. Getting the ratio wrong means black bars, awkward cropping or a stretched picture. This calculator simplifies any width and height pair into its cleanest ratio form and works in the other direction too, so you can start from a target ratio and find matching dimensions.
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The tool includes one tap presets for the ratios people use most, including 16:9 for video, 4:5 and 1:1 for social posts, 9:16 for vertical video and 3:2 for photography. Type any new width or height and the matching dimension updates instantly, so you always export or crop at a size that keeps your content looking right.

// ASPECT RATIO CALCULATOR · HOW IT WORKS

How to use the Aspect Ratio Calculator

Enter dimensions

Enter your current width and height to see the simplified aspect ratio.

Pick a ratio

Or pick a preset ratio such as 16:9, 4:3 or 1:1.

Get resized dimensions

Type a new width or height and the other dimension is calculated in proportion.

// ASPECT RATIO CALCULATOR · ABOUT THIS TOOL

About the Aspect Ratio Calculator

Aspect ratios show up everywhere: video exports, image uploads, screen sizes and social media crops. This calculator reduces any width and height to its cleanest ratio, or works backwards from a target ratio to find matching dimensions.

One-tap presets cover the ratios people use most, like 16:9, 9:16 and 1:1, and the matching dimension updates instantly as you type.

Where it helps most

Keeping every resize proportional.

Video thumbnails

Lock 16:9, enter the width your thumbnail must be, and get the matching height instantly so nothing ever gets squashed.

Social posts

Feed squares want 1:1, reels and stories want 9:16, video wants 16:9: get each platform's shape right the first time.

Responsive layouts

Web developers rely on ratios in responsive layouts so embedded videos never jump around as the page loads, on any screen size.

Print work

Match a photo's ratio to the paper it lands on, or you will lose edges to cropping when it prints.

Using it well

Two jobs, one tool.

Simplify any ratio

Feed it any two numbers and it returns the simplest form, so a photo measuring 4000 by 3000 becomes 4:3.

Scale from one side

Lock a ratio, enter the one side you know, and the matching side computes instantly with zero distortion, at any size you need.

Shapes you know

16:9 for video, 4:3 for classic photos, 1:1 for squares and 9:16 for stories: the shapes designers reach for daily.

Aspect Ratio Calculator: built for trust

Enter any width and height for the simplified ratio, or lock a ratio and scale it. Instant results.

// ASPECT RATIO CALCULATOR · COMMON QUESTIONS

Aspect Ratio Calculator FAQs

What is an aspect ratio?

An aspect ratio is the relationship between the width and height of a rectangle, written as two numbers like 16:9. It describes the shape, not the size, so 1920 by 1080 and 1280 by 720 are both 16:9 because they have the same shape.

How do I resize an image without stretching it?

What ratio is 1920x1080?

When should I use 16:9 instead of 4:3?