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Aspect Ratio Calculator

Enter a width and height to get the simplified ratio, or choose a ratio and a new width or height to get the matching size.

Find the ratio

px
px

Resize to a ratio

px
px

Type a width or a height; the other follows the ratio.

16:9
Aspect ratio of 1920 × 1080
16:9
Decimal
1.7778
Resized
1280 × 720 px
aspect-ratio: 16 / 9;

How to use the aspect ratio calculator

  1. Type a width and height in pixels to see their ratio, reduced (1920 × 1080 is 16:9).
  2. To resize, pick a common ratio or type one, like 4:5 or 2.39:1.
  3. Enter the new width or the new height; the other is calculated.
  4. Copy the CSS aspect-ratio line if you need it in code.

How the ratio is reduced

The width and height are divided by their greatest common divisor. 1920 and 1080 share 120, which gives 16:9. Some sizes do not reduce neatly: 1366 × 768 is 683:384. When a size is within 1.5% of a standard ratio, the calculator names it too, so you know it is “about 16:9”.

The resize formula

new height = new width × (ratio height ÷ ratio width). For 4:5 at 1080 wide, that is 1080 × 5 ÷ 4 = 1350. Results are rounded to whole pixels.

For platform sizes and print dimensions together, use the design size calculator.

Questions

What aspect ratio is 1920 × 1080?

16:9, the standard for HD and 4K video and most monitors.

What is the Instagram portrait ratio?

4:5, for example 1080 × 1350 pixels. Stories and Reels use 9:16.