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<ratio>

The <ratio> CSS data type, used for describing aspect ratios in media queries, denotes the proportion between two unitless values.

Syntax

In Media Queries Level 3, the <ratio> data type consisted of a strictly positive <integer> followed by a forward slash ('/', Unicode U+002F SOLIDUS) and a second strictly positive <integer>. Spaces before and after the slash are optional. The first number represents the width, while the second represents the height.

In Media Queries Level 4, the <ratio> date type is updated to consist of a strictly positive <number> followed by a forward slash ('/', Unicode U+002F SOLIDUS) and a second strictly positive <number>. In addition a single <number> as a value is allowable.

Formal syntax

<ratio> = 
  <number [0,∞]> [ / <number [0,∞]> ]?

Examples

Use in a media query

@media screen and (min-aspect-ratio: 16/9) {
  /* … */
}

Common aspect ratios

Ratio Usage
A rectangle that is three units tall and four units wide 4/3 Traditional TV format in the twentieth century.
A rectangle that is nine units tall and sixteen units wide 16/9 Modern "widescreen" TV format.
A rectangle that is 1 unit tall and 1.85 units wide 185/100 = 91/50 The most common movie format since the 1960s.
A rectangle that is 1 unit tall and 2.39 units wide 239/100 "Widescreen," anamorphic movie format.

Specifications

Specification
Media Queries Level 4
# values

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
ratio 3 12 3.5 9 9.5 5 ≤37 18 4 14 4.2 1.0
number_value No No 70 No No No No No No No No No

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/CSS/ratio