Free browser-based tool

Aspect Ratio Calculator
& Generator.

Find the width-to-height ratio of any screen, image, or video in seconds. Calculate, simplify, convert, and resize dimensions without distortion.

Aspect Ratio Calculator

Calculations stay on your device

01 Source Dimensions

Simplified Ratio16:9
Decimal1.7778
Width ÷ Height177.78%
Closest Standard16:9
02 Resize With This Ratio

Edit either value. The other updates automatically.

Common Ratios

Ready to calculate.

Resize With This Ratio

Compare cropping and padding

These sizes use the original pixels without scaling. A centered crop removes content equally from opposite edges; padding adds empty space.

Target ratio

Crop to fill

1920 × 1080

Source area retained: 100%

Pad to fit

1920 × 1080

Source Dimensions: 1920 × 1080

Screen dimensions

Screen ratio and widescreen pixel calculator

Find your screen proportions

A screen proportion calculator compares width with height, not the diagonal screen measurement. Enter a resolution such as 1920 × 1080 above to get 16:9. A 2560 × 1440 screen has the same proportions at a higher resolution. For 1920 × 1200, the simplified ratio is 8:5, commonly called 16:10.

16:9 screen dimensions · 16:10 screen proportions · 1920 × 1080 ratio calculation

Calculate widescreen pixels from one dimension

For a 16:9 widescreen frame, height = width × 9 ÷ 16. A width of 1280 pixels needs 720 pixels of height; 1920 needs 1080. To find width instead, multiply height by 16 ÷ 9. Select the 16:9 preset and change either new dimension in the tool. It calculates sizes, not a screen’s physical dimensions or pixel density.

Choose portrait dimensions instead

Vertical 9:16 uses 1080 × 1920, while a 2:3 portrait can use 512 × 768. These are different shapes: matching height alone does not make them interchangeable. Use an exact size from a guide, or compare cropping and padding before changing formats.

9:16 ratio sizes in pixels · 2:3 ratio calculator · 3:4 pixel dimensions · 4:5 portrait dimensions · 512 × 768 ratio

Guide

Worked examples and calculation limits

Source Dimensions

Try these examples in the calculator: 512 × 768 reduces to 2:3 because both numbers divide by 256. A 2.5 × 3.5 print reduces to 5:7 by first multiplying both dimensions by 10. Use the same unit for both dimensions; mixing inches and pixels gives a meaningless ratio.

Resize With This Ratio

To resize 1920 × 1080 to a width of 1280, calculate 1280 × 1080 ÷ 1920 = 720. For a 3:4 portrait at 900 pixels wide, the height is 1200. Resizing changes dimensions; it does not create additional image detail or export a file.

4:3 → 16:9

A 1440 × 1080 source is 4:3. To fill a 16:9 frame at the same width, crop its height to 810, removing 270 pixels total. To keep every pixel instead, place it in a 1920 × 1080 canvas with 240 pixels of padding on each side. Stretching to that canvas distorts the image.

Simplified Ratio

Ratios are simplified before rounding. Enter positive dimensions up to 1 billion with at most six decimal places. Output dimensions are rounded to whole pixels, so some sizes approximate the exact ratio: a 16:9 image at 100 pixels wide rounds from 56.25 to 56 pixels tall. Exact 16:9 pixel sizes use a width divisible by 16. The closest standard is a suggestion, not an exact match.

Aspect ratio guide

What Is Aspect Ratio?

Aspect ratio is the proportional relationship between width and height. It describes shape rather than a fixed pixel size, so 1920 × 1080 and 1280 × 720 are both 16:9.

How the Aspect Ratio Calculator and Generator Works

Enter a width and height in the size ratio calculator to generate the dimensions in their simplest form. The aspect ratio finder calculates the greatest common divisor, or GCD, and divides both values by it. For example, 1920 × 1080 becomes the 16:9 aspect ratio because both dimensions divide evenly by 120.

Calculate new image or video dimensions without stretching. After setting the original dimensions, enter either a new width or a new height. The missing value is calculated automatically while the ratio remains locked. The live preview shows whether the result is landscape, portrait, or square, and the share button saves the calculation in the page URL. The tool calculates sizes; it does not modify or export files.

Aspect Ratio Conversions by Dimension

To convert a dimension ratio, write the width first and height second, then divide both by their greatest common divisor. A 512 × 768 image simplifies to 2:3. A 24 × 18 image simplifies to 4:3. A 4-width by 2-height frame simplifies to 2:1, while 2.5 × 3.5 simplifies to 5:7 after multiplying both values by ten.

These aspect ratio conversions describe shape, not image quality. A small 512 × 768 image and a larger 1024 × 1536 image share the same 2:3 ratio because their width-to-height relationship is identical.

16:9 and 4:3 Aspect Ratios

The 16:9 aspect ratio is the standard widescreen format for most modern video, televisions, monitors, and presentations. Common 16:9 resolutions include 1280 × 720, 1920 × 1080, 2560 × 1440, and 3840 × 2160. YouTube identifies 16:9 as its standard desktop video ratio, although its player can adapt to other shapes.

The 4:3 aspect ratio is more square. It is associated with classic television, older computer displays, some tablets, and Micro Four Thirds photography. Typical sizes include 1024 × 768 and 1600 × 1200. A 4:3 frame can be a deliberate creative choice when you want a compact, editorial, or retro composition rather than a widescreen look.

Instagram, TikTok, and YouTube Aspect Ratios

There is no single Instagram aspect ratio for every placement. A 1:1 square works well for profile images and traditional feed posts, while 4:5 gives portrait feed content more vertical space. Reels and Stories commonly use a full-screen 9:16 frame, often exported at 1080 × 1920. Keep important text and faces away from interface overlays near the edges.

The recommended TikTok aspect ratio is 9:16 for vertical, full-screen video. TikTok’s current first-party creative guidance also lists 1:1 square and 16:9 horizontal formats for some placements, but 9:16 makes the best use of a phone screen. A practical vertical export is 1080 × 1920.

For standard YouTube videos, use 16:9 when you want the familiar widescreen player. For the YouTube Shorts aspect ratio, 9:16 is the most natural vertical format. YouTube currently categorizes eligible square or vertical videos as Shorts, so 1:1 can also qualify, but 9:16 fills the mobile Shorts viewer more completely.

Aspect Ratio for Images, Screens, and Design

Photographers often work with 3:2, while square artwork uses 1:1 and ultrawide screens may use 21:9. The best ratio depends on the final container. Choose the destination first, select a matching preset, and calculate dimensions before exporting. This prevents unwanted cropping, black bars, or stretched subjects.

Aspect ratio and resolution are related but not interchangeable. Ratio describes the frame’s shape; resolution describes the number of pixels inside it. Increasing resolution can improve detail without changing the shape, provided both dimensions grow proportionally.

Calculate Before You Crop

When a source and destination have different ratios, proportional resizing alone cannot make them match. You must crop part of the source, add padding, or redesign the layout. Use the preview and closest-standard result to spot that mismatch early. For a clean resize, change one dimension and let the calculator solve the other.

Quick reference

Ratios You’ll Use Every Day

Start with the right proportions for popular screens, images, videos, and social platforms.

16:9

Widescreen Video

YouTube, TV, presentations

1920 × 1080
9:16

Vertical Video

Reels, Shorts, TikTok

1080 × 1920
1:1

Square

Profile images, social posts

1080 × 1080
4:5

Social Portrait

Instagram feed portraits

1080 × 1350
3:2

Photography

DSLR and 35mm photos

6000 × 4000
21:9

Ultrawide

Exact 21:9 canvas

2520 × 1080

The essentials

Same Shape. Any Size.

Change one dimension and calculate the other while preserving the original proportions.

Width ÷ GCD:Height ÷ GCD
01

Source Dimensions

Find the width-to-height ratio of any screen, image, or video in seconds. Calculate, simplify, convert, and resize dimensions without distortion.

02

Simplified Ratio

Enter width and height to reduce dimensions to their simplest form. The calculator uses the greatest common divisor, then lets you resize proportionally without stretching.

03

Resize With This Ratio

Edit either value. The other updates automatically.

Reference

Common Dimensions

Useful starting points for screens, video exports, photos, and social media.

ReferenceCommon Dimensions16:9
HD1280 × 72016:9
Full HD1920 × 108016:9
QHD2560 × 144016:9
4K UHD3840 × 216016:9
Portrait image512 × 7682:3
Photo print2.5 × 3.55:7
Classic photo24 × 184:3
Wide banner4 × 22:1
Instagram Post1080 × 13504:5
Vertical Video1080 × 19209:16

FAQ

Clear Answers

Common questions about finding, converting, and preserving proportions.

What is an aspect ratio?

An aspect ratio is the proportional relationship between width and height, written as width:height. A 16:9 frame is about 1.78 times wider than it is tall, regardless of its pixel resolution.

Is a 4:3 aspect ratio the same as 16:9?

No. A 4:3 frame is about 1.33 times wider than tall, while 16:9 is about 1.78 times wider than tall. The 4:3 shape is squarer; 16:9 is wider.

Is 1920 × 1080 an aspect ratio?

1920 × 1080 is a resolution, not the simplified ratio itself. Dividing both dimensions by 120 gives its 16:9 aspect ratio.

How do I resize 4:3 to 16:9?

A 4:3 image cannot become 16:9 through proportional resizing alone. Crop the top and bottom, extend the sides, or add padding. For example, crop 1440 × 1080 to 1440 × 810 for a 16:9 result.

How do I calculate a 4:3 aspect ratio?

Choose any positive multiplier and apply it to both parts. Multiplying 4:3 by 256 gives 1024 × 768. To test existing dimensions, divide width by height; a 4:3 frame equals approximately 1.3333.

What aspect ratio should I use for Instagram?

Use 1:1 for a square post, 4:5 for a portrait feed post, and 9:16 for full-screen Stories or Reels. A common 4:5 export is 1080 × 1350; a common 9:16 export is 1080 × 1920.

What aspect ratio should I use for TikTok?

Use 9:16 for a full-screen vertical TikTok, typically 1080 × 1920. TikTok supports other shapes for some placements, but 9:16 uses the most mobile screen space.

What aspect ratio should I use for YouTube?

YouTube’s standard desktop video ratio is 16:9. Use resolutions such as 1920 × 1080 or 3840 × 2160. For YouTube Shorts, 9:16 is the natural full-screen vertical choice.

What aspect ratio is 512 × 768?

A 512 × 768 image has a 2:3 aspect ratio. Dividing both dimensions by their greatest common divisor, 256, simplifies 512:768 to 2:3.

How do I find the aspect ratio from width and height?

Enter the width and height in the calculator. It divides both dimensions by their greatest common divisor to produce the simplest width-to-height ratio. For example, 24 × 18 simplifies to 4:3.

Practical references

Find your dimensions.

Choose a shape, check an existing size, or plan a crop before exporting.

Platform sizing guides

Choose the destination first.

Compare feed images, full-screen video and crop trade-offs before exporting.