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


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.


Use in a media query

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

Common aspect ratios

Ratio Usage
Ratio4_3.png 4/3 Traditional TV format in the 20th century.
Ratio16_9.png 16/9 Modern "widescreen" TV format.
Ratio1_1.85.png 185/100 = 91/50 The most common movie format since the 1960s.
Ratio1_2.39.png 239/100
"Widescreen," anamorphic movie format.


Specification Status Comment
Media Queries Level 4
The definition of '<ratio>' in that specification.
Candidate Recommendation
Media Queries
The definition of '<ratio>' in that specification.
Recommendation Initial definition.

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
<ratio>Chrome Full support 3Edge Full support 12Firefox Full support 3.5IE Full support 9Opera Full support 9.5Safari Full support 5WebView Android Full support ≤37Chrome Android Full support 18Firefox Android Full support 4Opera Android Full support 14Safari iOS Full support 4.2Samsung Internet Android Full support 1.0
Accepts <number> / <number> or single <number> as a value.Chrome No support NoEdge No support NoFirefox Full support 70
Full support 70
Disabled From version 70: this feature is behind the layout.css.aspect-ratio-number.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.
IE No support NoOpera No support NoSafari No support NoWebView Android No support NoChrome Android No support NoFirefox Android No support NoOpera Android No support NoSafari iOS No support NoSamsung Internet Android No support No


Full support  
Full support
No support  
No support
User must explicitly enable this feature.
User must explicitly enable this feature.

See also