CSS transition-duration

The CSS transition-duration property allows you to specify how long your transition will take to complete. This allows you to adjust the speed of the transition, so that the effect happens quickly, slowly, or somewhere in between.

The transition-duration property accepts a "time" value. For example, a value of 3s will result in a transition running for 3 seconds. By changing the value of the transition-duration property, you effectively change the speed at which your transition runs. A higher value results in a slower transition, whereas a smaller value results in a faster transition.

Without this property, your styles would change instantaneously - there would be no transition. This is also what would happen if the transition-duration was set to 0s, meaning that the transition takes zero seconds to complete (i.e. you would not see any transition take place).

Syntax

transition-duration:  <time> [, <time>]*

Possible Values

<time>
The period of time that the transition should take to complete. For example, a value of 2s means that the transition will take 2 seconds to complete. By default the value is 0, meaning that the transition takes place in zero seconds (i.e. no transition). A negative value is treated as '0s'.

You can provide a different value for each of the properties listed (under the transition-property property) if you like. This will result in different properties transitioning at different speeds.

In addition, all CSS properties also accept the following CSS-wide keyword values as the sole component of their property value:

initial
Represents the value specified as the property's initial value.
inherit
Represents the computed value of the property on the element's parent.
unset
This value acts as either inherit or initial, depending on whether the property is inherited or not. In other words, it sets all properties to their parent value if they are inheritable or to their initial value if not inheritable.

Basic Property Information

Initial Value
0
Applies To
All elements, and the :before and :after pseudo elements
Inherited?
No
Media
Interactive

Example Code

Basic CSS

transition-duration: 1s;

Working Example within an HTML Document

<!DOCTYPE html>
<title>Example</title>
<style>
.resize { 
  background-color: yellowgreen;
  color: olivedrab;
  width: 40%;
  height: 20px; 
  padding: 10px;
  font-size: 1em;
  font-family: sans-serif;
  transition-property: width, height, font-size, font-weight, background-color;  
  transition-duration: 0.5s, 1s, 2s, 0.3s, 3s;
  transition-timing-function: cubic-bezier(0.25, 0.1, 0.25, 1.4);
  transition-delay: 0s;  
}
.resize:hover {  
  width: 70%;
  height: 150px;
  font-size: 2.3em;
  font-weight: bold;
  background-color: beige;
} 
</style>

<div class="resize">
  Hover over me...
</div>

Try it with the Online Editor

CSS Specifications

Browser Support

The following table provided by Caniuse.com shows the level of browser support for this feature.

Vendor Prefixes

For maximum browser compatibility many web developers add browser-specific properties by using extensions such as -webkit- for Safari, Google Chrome, and Opera (newer versions), -ms- for Internet Explorer, -moz- for Firefox, -o- for older versions of Opera etc. As with any CSS property, if a browser doesn't support a proprietary extension, it will simply ignore it.

This practice is not recommended by the W3C, however in many cases, the only way you can test a property is to include the CSS extension that is compatible with your browser.

The major browser manufacturers generally strive to adhere to the W3C specifications, and when they support a non-prefixed property, they typically remove the prefixed version. Also, W3C advises vendors to remove their prefixes for properties that reach Candidate Recommendation status.

Many developers use Autoprefixer, which is a postprocessor for CSS. Autoprefixer automatically adds vendor prefixes to your CSS so that you don't need to. It also removes old, unnecessary prefixes from your CSS.

You can also use Autoprefixer with preprocessors such as Less and Sass.