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Aspect Ratio Calculator

Enter the width and height to get the simplified aspect ratio. Add a new width to find the height that keeps the same proportions.

The width of the screen, photo or video in pixels.

The height in pixels.

Advanced

Optional. Enter the width you want to resize to and you get the matching height.

This result is an estimate only. Check with your bank or the relevant authority before making decisions.

How it is calculated

  • Divide the width and height by their greatest common divisor to get the simplest ratio
  • Decimal ratio = width ÷ height
  • Height at a new width = new width × height ÷ width

To see how sharp a screen is, use the screen PPI calculator. To estimate how long a video takes to download, use the download time calculator.

Worked example

A 1920 × 1080 screen:

  • The greatest common divisor of 1920 and 1080 is 120
  • 1920 ÷ 120 = 16 and 1080 ÷ 120 = 9, so the ratio is 16:9
  • Resized to a width of 1280, the height is 1280 × 1080 ÷ 1920 = 720

Why your number may differ

Rounding to whole pixels can change the ratio slightly when you resize. Some devices crop or add black bars rather than stretch. Marketing names such as 16:9 or 21:9 are often approximate.

Frequently asked questions

What is an aspect ratio?

It is the proportion of width to height, written as two numbers such as 16:9. A 1920 × 1080 image and a 1280 × 720 image both have a 16:9 ratio.

Why does my ratio look odd, like 683:384?

The calculator shows the exact simplest ratio. Some sizes, such as 1366 × 768, are close to 16:9 but not exactly. They are sold as 16:9 screens even though the exact ratio is different.

How do I resize without stretching?

Keep the same ratio. Enter the width you want in the new width box and use the height you get back.

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