CSS aspect-ratio Property Reference

The CSS aspect-ratio property is a standard property in CSS Box Sizing. Review its formal syntax, computed behavior, and practical declarations.

Updated 2026-08-12

aspect-ratio overview

The CSS aspect-ratio property is a standard property in CSS Box Sizing. Review its formal syntax, computed behavior, and practical declarations.

The property is not inherited by default. Use an explicit global keyword when inheritance is intended.

Syntax and formal definition

aspect-ratio formal syntax

Field	Value
Formal syntax	auto \|\| <ratio>
Initial value	auto
Applies to	allElementsExceptInlineBoxesAndInternalRubyOrTableBoxes
Inherited	No
Percentages	no
Computed value	asSpecified
Animation type	byComputedValueType
Media	all
Specification group	CSS Box Sizing
Status	Standard

Practical examples

These declarations demonstrate valid ways to set aspect-ratio. The initial and inherit global keywords remain available even when a property-specific value is preferable.

aspect-ratio live example

CSS

.reset-example {
  aspect-ratio: initial;
}

.inherit-example {
  aspect-ratio: inherit;
}

@supports (aspect-ratio: initial) {
  .supported {
    aspect-ratio: initial;
  }
}