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

IT defines the ability for a flex item to grow if necessary. It accepts a unitless value that serves as a proportion. It dictates what amount of the available space inside the flex container the item should take up.

For example, if all items have flex-grow set to 1, every child will set to an equal size inside the container. If you were to give one of the children a value of 2, that child would take up twice as much space as the others.


flex-grow: <number>

.flex-item {
  flex-grow: 2;


The following demo shows how the remaining space is being calculated according to the different values of flex-grow (see on CodePen for better understanding).

Check out this Pen!

All items have a flex-grow value of 1 except the 3rd one which has a flex-grow value of 2. It means when the available space is distributed, the 3rd flex-item will have twice as much space as others.

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).


  1. Sergey
    Permalink to comment#

    All Safari not supported flex-grow

  2. Jonatan
    Permalink to comment#

    Perfectly explained. Clear and to the point. Thanks.

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