This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for the proper prefixes to use in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the spec changes.


The tab-size CSS property is used to customize the width of a tab (U+0009) character.

  • Initial value 8
  • Applies to block containers
  • Inherited yes
  • Media visual
  • Computed value the specified integer or an absolute length
  • Animatable no
  • Canonical order the unique non-ambiguous order defined by the formal grammar


/* <integer> values */
tab-size: 4;
tab-size: 0;

/* <length> values */
tab-size: 10px;
tab-size: 2em;

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


The number of spaces in a tab. Must be nonnegative.
The width of a tab. Must be nonnegative.
Inherits from the parent element.

Formal syntax

<integer> | <length>


pre {
  tab-size: 4; /* Set tab size to 4 spaces */
pre {
  tab-size: 0; /* Remove indentation */
pre {
  tab-size: 99; /* Don't use tabs! */


Specification Status Comment
CSS Text Level 3
The definition of 'tab-size' in that specification.
Working Draft Initial definition

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support 21 4.0 (2.0)-moz Not supported


<length> Not supported Not supported[1] Not supported Not supported Not supported
Feature Safari Mobile Opera Mini Opera Mobile Android
Basic support 7.1 5-o 11.5-o

[1] Gecko doesn't implement this yet. See bug 943918.

See also

Document Tags and Contributors

Last updated by: Jeremie,
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