How TO - Aspect Ratio

Learn how to maintain the aspect ratio of an element with CSS.

Aspect Ratio

Create flexible elements that keep their aspect ratio (4:3, 16:9, etc.) when resized:

What is aspect ratio?

The aspect ratio of an element describes the proportional relationship between its width and its height. Two common video aspect ratios are 4:3 (the universal video format of the 20th century), and 16:9 (universal for HD television and European digital television, and default for YouTube videos).

How To - Height Equal to Width

Step 1) Add HTML:

Use a container element, like <div>, and if you want text inside of it, add a child element:

Example

Step 2) Add CSS:

Add a percentage value for padding-top to maintain the aspect ratio of the DIV. The following example will create an aspect ratio of 1:1 (the height and width is always equal):

Example 1:1 Aspect Ratio

.container {
  background-color: red;
  width: 100%;
padding-top: 100%; /* 1:1 Aspect Ratio */
position: relative; /* If you want text inside of it */
}

/* If you want text inside of the container */
.text {
position: absolute;
top: 0;
  left: 0;
  bottom: 0;
  right: 0;
}

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Other aspect ratios:

Example 16:9 Aspect Ratio

.container {
padding-top: 56.25%; /* 16:9 Aspect Ratio (divide 9 by 16 = 0.5625) */
}

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Example 4:3 Aspect Ratio

.container {
padding-top: 75%; /* 4:3 Aspect Ratio (divide 3 by 4 = 0.75) */
}

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Example 3:2 Aspect Ratio

.container {
padding-top: 66.66%; /* 3:2 Aspect Ratio (divide 2 by 3 = 0.6666) */
}

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Example 8:5 Aspect Ratio

.container {
padding-top: 62.5%; /* 8:5 Aspect Ratio (divide 5 by 8 = 0.625) */
}

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The aspect-ratio CSS Property

In newer browsers, you can simply use the CSS aspect-ratio property:

Example 3:2 Aspect Ratio

.container {
aspect-ratio: 3 / 2;
}

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The numbers in the table specify the first browser version that fully supports the property.

Property
aspect-ratio	88	88	89	15	74

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