This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage 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 specification changes.

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

Initial value8
Applies toblock containers
Computed valuethe specified integer or an absolute length
Animation typediscrete
Canonical orderthe 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.

Formal syntax

<integer> | <length>


pre {
  tab-size: 4; /* Set tab size to 4 spaces */
pre {
  tab-size: 0; /* Remove indentation */
pre {
  tab-size: 2; /* Set tab size to 2 spaces */


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[1] No support 10.60-o
<length> 42 No support[2] No support No support No support
Feature Android Firefox Mobile (Gecko) IE Mobile Opera Mini Opera Mobile Safari Mobile
Basic support 4.4 ?[1] ? 5-o 11.5-o
<length> ? ? ? ? ? ?

[1] This feature is currently prefixed with -moz. It will be unprefixed in bug 737785.

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

See also

Document Tags and Contributors

 Last updated by: Alhadis,