CSS min-block-size Property

Last Updated : 10 Jun, 2026

The CSS min-block-size property sets the minimum size of an element in the block direction, preventing it from shrinking below a specified limit.

  • Prevents an element from becoming smaller than the specified minimum block size.
  • Adapts to different writing modes by controlling the block dimension.
  • Helps maintain consistent layouts and improves content readability.

Syntax:

min-block-size: length | percentage | auto | min-content | max-content | fit-content | inherit | initial | unset;

Property values

  • length: It sets a fixed value defined in px, cm, pt etc. Negative values are also allowed. Its default value is 0px.
  • percentage (%): It is the same as length but the size is set in term of percentage of the window size.
  • auto: It is used when it is desired that the browser determines the block-size.
  • none: It is used when you don't want to limit on the size of the box.
  • max-content: It is used when you preferred min-width on the size of the box.
  • min-content: It is used when you preferred min-width on the size of the box.
  • fit-content: It is used when you preferred exact-width on the size of the box.
  • initial: It is used to set the value of the min-block-size property to its default value.
  • inherit: It is used when it is desired that the element inherits the min-block-size property from its parent element.
  • unset: It is used to unset the default mix-block-size.

Examples of min-block-size Property

Below examples illustrate the min-block-size property in CSS: 

Example 1: The min-block-size property ensures that the cyan box maintains a minimum block size of 40px, preventing it from shrinking below that size even if the content requires less space.

HTML
<!--Driver Code Starts-->
<!DOCTYPE html>
<html>

<head>
    <title>CSS min-block-size Property</title>
<!--Driver Code Ends-->

    <style>
        body {
            background-color: #dcdcdc;
            font-family: "Times New Roman", serif;
        }

        h1 {
            color: green;
            margin-bottom: 15px;
        }

        h2 {
            font-size: 22px;
            margin-bottom: 25px;
        }

        .box {
            background-color: cyan;
            width: 200px;
            min-block-size: 40px;
            text-align: center;
            margin-left: 35px;
            font-size: 18px;
            padding: 5px 0;
        }
    </style>

<!--Driver Code Starts-->
</head>

<body>
    <h1>GeeksforGeeks</h1>

    <h2>CSS | min-block-size Property</h2>

    <div class="box">
        A Computer Science<br>
        Portal for Geeks
    </div>
</body>

</html>
<!--Driver Code Ends-->

Example 2:  The min-block-size property sets a minimum block size of 80px for the vertically oriented cyan box, preventing it from shrinking below that size regardless of the content length.

HTML
<!--Driver Code Starts-->
<!DOCTYPE html>
<html>

<head>
    <title>CSS | min-block-size Property</title>
<!--Driver Code Ends-->

    <style>
        body {
            background-color: #dcdcdc;
            font-family: "Times New Roman", serif;
        }

        h1 {
            color: green;
            font-size: 34px;
            margin: 10px 0;
        }

        h2 {
            font-size: 20px;
            margin-bottom: 25px;
        }

        .wrapper {
            position: relative;
            margin-left: 30px;
        }

        .bar {
            width: 200px;
            height: 20px;
            background: green;
        }

        .box {
            background: cyan;
            writing-mode: vertical-rl;
            min-block-size: 80px;
            inline-size: 95px;
            text-align: center;
            font-size: 18px;
            position: absolute;
            top: 0;
            left: 15px;
        }
    </style>

<!--Driver Code Starts-->
</head>

<body>
    <h1>GeeksforGeeks</h1>

    <h2>CSS | min-block-size Property</h2>

    <div class="wrapper">
        <div class="bar"></div>

        <div class="box">
            A Computer Science Portal for Geeks
        </div>
    </div>

</body>

</html>
<!--Driver Code Ends-->
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