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The :nth-child() CSS pseudo-class matches elements based on their position in a group of siblings.

/* Selects every fourth element
   among any group of siblings */
:nth-child(4n) {
  color: lime;
}

Syntax

The nth-child pseudo-class is specified with a single argument, which represents the pattern for matching elements.

Keyword values

odd
Represents elements whose numeric position in a series of siblings is odd: 1, 3, 5, etc.
even
Represents elements whose numeric position in a series of siblings is even: 2, 4, 6, etc.

Functional notation

<An+B>
Represents elements whose numeric position in a series of siblings matches the pattern An+B, for every positive integer or zero value of n. The index of the first element is 1. The values A and B must both be <integer>s.

Formal syntax

:nth-child( <nth> [ of <selector># ]? )

where
<nth> = <an-plus-b> | even | odd

Examples

Example selectors

tr:nth-child(odd) or tr:nth-child(2n+1)
Represents the odd rows of an HTML table: 1, 3, 5, etc.
tr:nth-child(even) or tr:nth-child(2n)
Represents the even rows of an HTML table: 2, 4, 6, etc.
:nth-child(7)
Represents the seventh element.
:nth-child(5n)
Represents elements 5 [=5×1], 10 [=5×2], 15 [=5×3], etc.
:nth-child(3n+4)
Represents elements 4 [=(3×0)+4], 7 [=(3×1)+4], 10 [=(3×2)+4], 13 [=(3×3)+4], etc.
:nth-child(-n+3)
Represents the first three elements. [=-0+3, -1+3, -2+3]
p:nth-child(n)
Represents every <p> element in a group of siblings. This selects the same elements as a simple p selector (although with a higher specificity).
p:nth-child(1) or p:nth-child(0n+1)
Represents every <p> that is the first element in a group of siblings. This is the same as the :first-child selector (and has the same specificity).
p:nth-child(n+8):nth-child(-n+15)
Represents the eighth through the fifteenth <p> elements of a group of siblings.

Detailed example

HTML

<h3><code>span:nth-child(2n+1)</code>, WITHOUT an
   <code>&lt;em&gt;</code> among the child elements.</h3>
<p>Children 1, 3, 5, and 7 are selected.</p>
<div class="first">
  <span>Span 1!</span>
  <span>Span 2</span>
  <span>Span 3!</span>
  <span>Span 4</span>
  <span>Span 5!</span>
  <span>Span 6</span>
  <span>Span 7!</span>
</div>

<br>

<h3><code>span:nth-child(2n+1)</code>, WITH an
   <code>&lt;em&gt;</code> among the child elements.</h3>
<p>Children 1, 5, and 7 are selected.<br>
   3 is used in the counting because it is a child, but it isn't
   selected because it isn't a <code>&lt;span&gt;</code>.</p>
<div class="second">
  <span>Span!</span>
  <span>Span</span>
  <em>This is an `em`.</em>
  <span>Span</span>
  <span>Span!</span>
  <span>Span</span>
  <span>Span!</span>
  <span>Span</span>
</div>

<br>

<h3><code>span:nth-of-type(2n+1)</code>, WITH an
   <code>&lt;em&gt;</code> among the child elements.</h3>
<p>Children 1, 4, 6, and 8 are selected.<br>
   3 isn't used in the counting or selected because it is an <code>&lt;em&gt;</code>, 
   not a <code>&lt;span&gt;</code>, and <code>nth-of-type</code> only selects
   children of that type. The <code>&lt;em&gt;</code> is completely skipped
   over and ignored.</p>
<div class="third">
  <span>Span!</span>
  <span>Span</span>
  <em>This is an `em`.</em>
  <span>Span!</span>
  <span>Span</span>
  <span>Span!</span>
  <span>Span</span>
  <span>Span!</span>
</div>

CSS

html {
  font-family: sans-serif;
}

span,
div em {
  padding: 5px;
  border: 1px solid green;
  display: inline-block;
  margin-bottom: 3px;
}

.first span:nth-child(2n+1),
.second span:nth-child(2n+1),
.third span:nth-of-type(2n+1) {
  background-color: lime;
}

Result

Specifications

Specification Status Comment
Selectors Level 4
The definition of ':nth-child' in that specification.
Working Draft Adds of <selector> syntax and specifies that matching elements are not required to have a parent.
Selectors Level 3
The definition of ':nth-child' in that specification.
Recommendation Initial definition.

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support1 Yes3.599.513.1
of <selector> syntax No ? No2 ? ?9
Matches elements with no parent57 ?52 ?44 ?
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support Yes Yes Yes49.513.1 Yes
of <selector> syntax ? ? ? No2 ?9 No
Matches elements with no parent5757 ?5244 ?7.0

1. Before Opera 15, Opera does not handle dynamically inserted elements for :nth-child().

2. See bug 854148.

See also