Screen Ratio Calculator

This calculator works out the aspect ratio of any screen, image or video from its width and height in pixels, then shows you what a matching size looks like at a different resolution. Getting the ratio right matters when you are buying a monitor or TV, cropping a photo, setting up a video export, or checking whether a design will letterbox or stretch on a different screen. Enter the width and height in any consistent unit, or pick a common resolution from the preset list, and the calculator returns the simplified ratio (found using the greatest common divisor), the decimal ratio from dividing width by height, and the closest standard named ratio such as 16:9, 16:10, 4:3 or 21:9. A ratio breakdown shows the GCD, total pixel count and how close your dimensions sit to that named standard, alongside a simple visual box so you can see the shape at a glance. To resize while keeping the same proportions, switch to the scaling section and enter a target width, target height or scale factor; the calculator works out the matching dimension and lists common resolutions that share your ratio, flagging any exact match. Use it before ordering hardware, exporting video, or resizing images for a website or social platform, so you know how the proportions will look before you commit to a size.

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Standard ratios as at 2026  Covers 16:9, 16:10, 4:3, 21:9, 32:9 and other common display standards.

1. Screen or Image Dimensions

px
px

2. Scale to a New Size

px

Aspect Ratio Results

Simplified Ratio
16:9
GCD = 120
Decimal Ratio
1.7778
Width / Height
Closest Standard
16:9
Exact match
Scaled Dimensions
1280 x 720
At target size
16:9
Visual representation of ratio (not to screen scale)

Ratio Breakdown

Input width1,920 px
Input height1,080 px
Greatest common divisor120
Simplified ratio (W:H)16:9
Decimal ratio (W/H)1.7778
Total pixels2,073,600 px
Closest named ratio16:9 (Widescreen) (exact match)

Scaled Dimensions

Scale modeBy target width
Target input1,280 px
Scale factor applied0.6667x
Scaled width1,280 px
Scaled height720 px
Scaled pixels (total)921,600 px
Scaled dimensions1280 x 720

Common Resolutions at This Ratio

NameWidthHeightTotal PixelsMatch?
Result: Enter dimensions above to see results.

How to Calculate Screen Aspect Ratio

The aspect ratio of a screen or image is the proportional relationship between its width and height. It is expressed as two integers separated by a colon (such as 16:9) or as a single decimal number (such as 1.78).

To find the simplified aspect ratio from pixel dimensions:

  1. Find the greatest common divisor (GCD) of the width and the height using the Euclidean algorithm.
  2. Divide both the width and the height by the GCD.
  3. The result is the lowest integer ratio (for example, 1920 / 120 = 16 and 1080 / 120 = 9, giving 16:9).

For a decimal ratio, simply divide width by height: 1920 / 1080 = 1.7778.

Common Screen Ratios and Their Uses

RatioDecimalCommon ResolutionsTypical Use
16:91.7781280x720, 1920x1080, 2560x1440, 3840x2160TVs, monitors, video content, most laptops
16:10 (8:5)1.6001280x800, 1920x1200, 2560x1600Productivity laptops, some tablets
4:31.333640x480, 800x600, 1024x768Older monitors, standard definition TV, tablets
21:92.3332560x1080, 3440x1440Ultrawide monitors, cinema
32:93.5563840x1080, 5120x1440Super ultrawide monitors
1:11.0001080x1080Social media square images
9:160.5631080x1920Vertical video (mobile), stories
4:50.8001080x1350Instagram portrait posts
3:21.5002160x1440Surface devices, some cameras
5:41.2501280x1024Older 17-19 inch CRT/LCD monitors

Scaling While Preserving Aspect Ratio

To scale an image or resolution while keeping the same ratio:

When scaling pixel dimensions, round to the nearest whole pixel. Some encoded video formats require dimensions that are multiples of 2 (or 4 or 8), so you may need to round to the nearest even number.

Worked Example

A 1920 x 1080 screen is the default input for this calculator. Here is how the ratio is derived:

Related Calculators

Sources and method: Aspect ratio calculation uses the Euclidean algorithm for greatest common divisor. Standard ratio names follow display industry conventions (VESA, ISO, CEA-861). Closest standard ratio is determined by minimum absolute difference in decimal ratio from named standards.

Scaled dimensions are rounded to the nearest whole pixel. For video encoding, dimensions may need to be multiples of 2 or 4 depending on the codec. This calculator covers standard display ratios only; non-standard ratios may not have a widely recognised name.

Frequently asked questions

How do I calculate the aspect ratio of a screen from its width and height?

Divide both the width and height by their greatest common divisor (GCD). For example, a 1920 x 1080 screen: GCD(1920, 1080) = 120, so 1920 / 120 = 16 and 1080 / 120 = 9, giving an aspect ratio of 16:9. For a decimal ratio, simply divide width by height: 1920 / 1080 = 1.778.

What is the difference between 16:9 and 16:10?

16:9 is the dominant widescreen standard used for televisions, most monitors, and video content. It has a decimal ratio of approximately 1.778. 16:10 (also written 8:5) is slightly taller and was common on laptop screens and older monitors. A 1920 x 1200 display is 16:10 and provides more vertical space for productivity work. 16:10 screens are experiencing a revival in laptops as users prefer the extra vertical height for documents and web pages.

How do I scale a resolution while keeping the same aspect ratio?

Multiply both width and height by the same scale factor, or use the ratio to solve for the missing dimension. If you know the target width, calculate target height = target width divided by (original width divided by original height). If you know the target height, calculate target width = target height multiplied by (original width divided by original height). This calculator does this automatically when you enter a target width or height in the scaling section.

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