aspect-ratio

The aspect-ratio CSS property sets a preferred aspect ratio for the box, which will be used in the calculation of auto sizes and some other layout functions.

This property is not yet implemented in browsers, however some browsers are implementing this internally in order to provide the aspect ratio mapping described below.

Syntax

aspect-ratio: 1 / 1;

/* Global values */
aspect-ratio: inherit;
aspect-ratio: initial;
aspect-ratio: unset;

Values

<auto>: Replaced elements with an intrinsic aspect ratio use that aspect ratio, otherwise the box has no preferred aspect ratio. Size calculations involving intrinsic aspect ratio always work with the content box dimensions.
<ratio>: The box’s preferred aspect ratio is the specified ratio of width / height. Size calculations involving preferred aspect ratio work with the dimensions of the box specified by box-sizing.

Formal syntax

auto | <ratio>

Mapping width and height to aspect-ratio

Firefox has added an internal aspect-ratio property (in version 69 onwards) that applies to replaced elements and other related elements that accept width and height attributes. This appears in the browser's internal UA stylesheet. Chrome is also shipping this feature.

Specifications

Specification	Status	Comment
CSS Box Sizing Module Level 4 The definition of 'aspect-ratio' in that specification.	Editor's Draft	Initial definition

Initial value	`auto`
Applies to	all elements except inline boxes and internal ruby or table boxes
Inherited	no
Computed value	as specified
Animation type	discrete

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`aspect-ratio` Experimental	Chrome Partial support 79 Notes Partial support 79 Notes Notes Chrome 79 adds internal support only for mapped values	Edge Partial support 79 Notes Partial support 79 Notes Notes Edge 79 adds internal support only for mapped values	Firefox Partial support 71 Notes Partial support 71 Notes Notes Firefox 71 adds internal support only for mapped values No support 69 — 71 Notes Disabled Notes Firefox 69 adds internal support only for mapped values Disabled From version 69 until version 71 (exclusive): this feature is behind the `layout.css.width-and-height-map-to-aspect-ratio.enabled` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	IE No support No	Opera No support No	Safari No support No	WebView Android Partial support 79 Notes Partial support 79 Notes Notes Webview 79 adds internal support only for mapped values	Chrome Android Partial support 79 Notes Partial support 79 Notes Notes Chrome 79 adds internal support only for mapped values	Firefox Android No support No	Opera Android No support No	Safari iOS No support No	Samsung Internet Android No support No
Internal mapping of width and height Experimental	Chrome Full support 79	Edge Full support 79	Firefox Full support 71 Full support 71 No support 69 — 71 Disabled Disabled From version 69 until version 71 (exclusive): this feature is behind the `layout.css.width-and-height-map-to-aspect-ratio.enabled` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	IE No support No	Opera No support No	Safari No support No	WebView Android Full support 79	Chrome Android Full support 79	Firefox Android No support No	Opera Android No support No	Safari iOS No support No	Samsung Internet Android No support No

Legend

Full support: Full support
Partial support: Partial support
No support: No support
Experimental. Expect behavior to change in the future.: Experimental. Expect behavior to change in the future.
See implementation notes.: See implementation notes.
User must explicitly enable this feature.: User must explicitly enable this feature.