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.

/* <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;
Initial value 8
Applies to block containers
Inherited yes
Media visual
Computed value the specified integer or an absolute length
Animation type a length
Canonical order the unique non-ambiguous order defined by the formal grammar



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 Module Level 3
The definition of 'tab-size' in that specification.
Working Draft Initial definition

Browser compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari
Basic support 21[1] No support 4.0 (2.0)-moz[2] No support 10.60-o
<length> 42 No support 53.0 (53.0)[3] No support 29 No support
Feature Android Firefox Mobile (Gecko) IE Mobile Opera Mini Opera Mobile Safari Mobile
Basic support 4.4 4.0 (2.0)[2] No support 5-o 11.5-o
<length> 56 53.0 (53.0)[3] No support No support 37 No support

[1] The property is not yet animatable.

[2] The property is currently prefixed with -moz-. It will be unprefixed in bug 737785. The property was not animatable until 53.0 (bug 1308110).

[3] This was implemented in bug 943918; in addition, tab-size is now animatable.

See also

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