This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The inline-size CSS property defines the horizontal or vertical size of an element's block, depending on its writing mode. It corresponds to either the width or the height property, depending on the value of writing-mode.

/* <length> values */
inline-size: 300px;
inline-size: 25em;

/* <percentage> values */
inline-size: 75%;

/* Keyword values */
inline-size: 25em border-box;
inline-size: 75% content-box;
inline-size: max-content;
inline-size: min-content;
inline-size: available;
inline-size: fit-content;
inline-size: auto;

/* Global values */
inline-size: inherit;
inline-size: initial;
inline-size: unset;

If the writing mode is vertically oriented, the value of inline-size relates to the height of the element; otherwise, it relates to the width of the element. A related property is block-size, which defines the other dimension of the element.

Initial value auto
Applies to same as width and height
Inherited no
Percentages inline-size of containing block
Media visual
Computed value same as width and height
Animation type discrete
Canonical order the unique non-ambiguous order defined by the formal grammar



The inline-size property takes the same values as the width and height properties.

Formal syntax




<p class="exampleText">Example text</p>


.exampleText {
  writing-mode: vertical-rl;
  background-color: yellow;
  inline-size: 110px;


Specification Status Comment
CSS Logical Properties and Values Level 1
The definition of 'inline-size' in that specification.
Editor's Draft Initial definition

Browser compatibility

Feature Chrome Edge Firefox Internet Explorer Opera Safari
Basic support No ?


38 — 511

No No No
Feature Android webview Chrome for Android Edge mobile Firefox for Android Opera Android iOS Safari Samsung Internet
Basic support No ? ?


38 — 511

No No ?

1. From version 38 until version 51 (exclusive): this feature is behind the layout.css.vertical-text.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.

See also

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