The opacity CSS property sets the transparency of an element or the degree to which content behind an element is visible.

opacity applies to the element as a whole, including its contents, even though the value is not inherited by child elements. Thus, the element and its children all have the same opacity relative to the element's background, even if they have different opacities relative to one another.

Using opacity with a value other than 1 places the element in a new stacking context.

If you do not want to apply opacity to child elements, use the background property instead. For example:

background: rgba(0, 0, 0, 0.4);



A <number> in the range 0.0 to 1.0, inclusive, representing the opacity of the channel (that is, the value of its alpha channel). Any value outside the interval, though valid, is clamped to the nearest limit in the range.
Value Meaning
0 The element is fully transparent (that is, invisible).
Any <number> strictly between 0 and 1 The element is translucent (that is, content behind the element can be seen).
1 (default value) The element is fully opaque (visually solid).

Formal syntax



Basic example

div { background-color: yellow; }
.light {
  opacity: 0.2; /* Barely see the text over the background */
.medium {
  opacity: 0.5; /* See the text more clearly over the background */
.heavy {
  opacity: 0.9; /* See the text very clearly over the background */
<div class="light">You can barely see this.</div>
<div class="medium">This is easier to see.</div>
<div class="heavy">This is very easy to see.</div>

Different opacity with :hover

img.opacity {
  opacity: 1;
  filter: alpha(opacity=100); /* IE8 and lower */
  zoom: 1; /* Triggers "hasLayout" in IE 7 and lower */
img.opacity:hover {
  opacity: 0.5;
  filter: alpha(opacity=50);
  zoom: 1;
<img src="//developer.mozilla.org/media/img/mdn-logo.png"
  alt="MDN logo" width="128" height="146"

Accessibility concerns

If text opacity is adjusted, it is important to ensure that the contrast ratio between the color of the text and the background the text is placed over is high enough that people experiencing low vision conditions will be able to read the content of the page.

Color contrast ratio is determined by comparing the luminosity of the opacity-adjusted text and background color values. In order to meet current Web Content Accessibility Guidelines (WCAG), a ratio of 4.5:1 is required for text content and 3:1 for larger text such as headings. Large text is defined as 18.66px and bold or larger, or 24px or larger.


Specification Status Comment
CSS Transitions
The definition of 'opacity' in that specification.
Working Draft Defines opacity as animatable.
CSS Color Module Level 3
The definition of 'opacity' in that specification.
Recommendation Initial definition
Initial value 1.0
Applies to all elements
Inherited no
Media visual
Computed value the specified value, clipped in the range [0,1]
Animation type a number
Canonical order the unique non-ambiguous order defined by the formal grammar

Browser compatibilityUpdate compatibility data on GitHub

Chrome Edge Firefox Internet Explorer Opera Safari
Basic support 1 12 1
1 — 3.5
Prefixed Implemented with the vendor prefix: -moz-
9 9 1.2
Android webview Chrome for Android Edge Mobile Firefox for Android Opera for Android iOS Safari Samsung Internet
Basic support 1 Yes Yes 4 9 3.2 Yes

See also

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