CSS 数据类型 <percentage> 表述一个百分比值。许多 CSS 属性 可以取百分比值,经常用以根据父对象来确定大小。Percentages are formed by a <number> immediately followed by the percentage sign %. Just as is the case with all other units in CSS, there isn't a space between the '%' and the number.

许多长度属性使用百分比,如{ { Cssxref(“width”)} },{ { Cssxref(“margin”)} }和{ { Cssxref(“填充”)} }。百分比也可以在{ {Cssxref(“font-size”)} }看到,其中的文字大小是其父级元素的大小直接相关。

Many length properties use percentages, such as width, margin and padding. Percentages can also be seen in font-size, where the size of the text is directly related to the size of its parent.

Note: only calculated values are inherited. So, even if a percentage value is used on the parent property, a real value, like a width in pixel for a <length> value, will be accessible on the inherited property, not the percentage value.
注:只有计算值可继承的。所以,即使一个百分比值用于父属性,一个真正的值,比如具体像素宽度{ { cssxref(“<length>”)} }的值,将访问继承的属性,而不是百分比的值。



在<percentage> CSS数据类型的值可以插值变成动画。在这种情况下,它们被内插为实数,浮点数。插值的速度取决于与动画相关联的定时器。

Values of the <percentage> CSS data type can be interpolated in order to allow animations. In that case they are interpolated as real, floating-point numbers. The speed of the interpolation is determined by the timing function associated with the animation.


<div style="background-color:#0000FF;">
  <div style="width:50%;margin-left:20%;background-color:#00FF00;">Width: 50%, Left margin: 20%</div>
  <div style="width:30%;margin-left:60%;background-color:#FF0000;">Width: 30%, Left margin: 60%</div>

The above HTML will output:

Width: 50%, Left margin: 20%
Width: 30%, Left margin: 60%


<div style="font-size:18px;">
  Full size text (18px)
  <span style="font-size:50%;">50%</span>
  <span style="font-size:200%;">200%</span>

The above HTML will output:

Full size text (18px) 50% 200%


Specification Status Comment
CSS Values and Units Module Level 3
Candidate Recommendation No significant change from CSS Level 2 (Revision 1)
CSS Level 2 (Revision 1)
Recommendation No change from CSS Level 1
CSS Level 1


Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 1.0 1.0 (1.0) <=5.0 yes 1.0 (85)
Feature Android Firefox Mobile (Gecko) IE Phone Opera Mobile Safari Mobile
Basic support yes yes yes yes yes


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