flex-basis

The flex-basis property is a sub-property of the Flexible Box Layout module.

It specifies the initial size of the flex item, before any available space is distributed according to the flex factors. When omitted from the flex shorthand, its specified value is the length zero.

A flex-basis value set to auto sizes the element according to its size property (which can itself be the keyword auto, which sizes the element based on its contents).

Syntax

flex-basis: <width>

.flex-item {
  flex-basis: 100px;
}

Please note that as for any width, negative lengths are invalid.

Demo

Check out this Pen!

Related Properties

Other Resources

Browser Support

  • (modern) means the recent syntax from the specification (e.g. display: flex;)
  • (hybrid) means an odd unofficial syntax from 2011 (e.g. display: flexbox;)
  • (old) means the old syntax from 2009 (e.g. display: box;)
Chrome Safari Firefox Opera IE Android iOS
21+ (modern)
20- (old)
3.1+ (old) 2-21 (old)
22+ (new)
12.1+ (modern) 10+ (hybrid) 2.1+ (old) 3.2+ (old)

Blackberry browser 10+ supports the new syntax.

For more informations about how to mix syntaxes in order to get the best browser support, please refer to this article (CSS-Tricks) or this article (DevOpera).

Comments

  1. User Avatar
    fantasai

    The article should maybe be updated to say that the spec recommends using the ‘flex’ shorthand over the ‘flex-basis’ longhand.

  2. User Avatar
    vsync
    Permalink to comment#

    codepen demo doesn’t show flex-basis

    • User Avatar
      2upmedia
      Permalink to comment#

      It uses the flex shorthand rule, the last value is for flex-basis and the demo has an explicit value set in em’s.

  3. User Avatar
    Chris
    Permalink to comment#

    Can anyone help me to solve this problem?

Submit a Comment

Posting Code

You may write comments in Markdown. This makes code easy to post, as you can write inline code like `<div>this</div>` or multiline blocks of code in triple backtick fences (```) with double new lines before and after.

Code of Conduct

Absolutely anyone is welcome to submit a comment here. But not all comments will be posted. Think of it like writing a letter to the editor. All submitted comments will be read, but not all published. Published comments will be on-topic, helpful, and further the discussion or debate.

Want to tell us something privately?

Feel free to use our contact form. That's a great place to let us know about typos or anything off-topic.

icon-closeicon-emailicon-linkicon-logo-staricon-menuicon-searchicon-staricon-tag