CSS Function - oklch()

The oklch() function in CSS expresses a color in oklch color space. It uses the same L-axis as oklab() function, but apart from that it uses the polar coordinates C (Chroma) and H (Hue).

To add the color transparency, an optional alpha component can be passed to the oklch() function.

Possible values

The functional notation for oklch() function is oklch(L C H[ / A]).

  • L: can contain either of the format(s), that represents the perceived lightness:

    • a <number>: any number between 0 and 1, where 0 corresponds to 0% (black) and 1 corresponds to 100% (white).

    • a <percentage>: any value between 0% and 100%.

    • keyword none

  • C: can contain either of the format(s), that specifies the measure of chroma, i.e., the amount of color. Minimal useful value is 0, maximum value is unbounded in theory, but does not exceed 0.5:

    • a <number>: any number between 0 and 0.5.

    • a <percentage>: any value between 0% and 100%, where 0% corresponds to 0 and 100% corresponds to 0.4.

    • keyword none

  • H: can contain either of the format(s), that specifies the hue angle:

    • a <number>: any number.

    • a <angle>: an angle value.

    • keyword none

  • A: represents the transparency of the color. It is an optional value.

    • <alpha-value>: any number between 0 and 1, where 1 corresponds to full opacity and 0 corresponds to full transparency.

    • keyword none

Syntax

oklch(29.2345% 0.36 24.57) | oklch(29 0.12 20deg) | oklch(29.2345% 0.4 49.0664 / 0.5);

CSS oklch() - Combination of Values

Following is an example showing the usage of oklch() function with different combinations of values:

<html>
<head>
<style>
   div {
      width: 100px;
      height: 100px;
      border: 2px solid black;
      margin-bottom: 10px;
   }
   
   .oklch-chroma-100 {
      background-color: oklch(50% 100% 200);
   } 

   .oklch-light-100 {
      background-color: oklch(100% 0.4 200);
   } 

   .oklch-light-none {
      background-color: oklch(none 0.29 60deg);
      color: white;
   }

   .oklch-hue-none {
      background-color: oklch(75 75% none);
   }

   .oklch-with-alpha {
      background-color: oklch(85 0.12 75deg / 0.8);
   }
</style>
</head>
<body>
   <div class="oklch-chroma-100">oklch(50% 100% 200)</div>
   <div class="oklch-light-100">oklch(100% 0.4 200)</div>
   <div class="oklch-light-none">oklch(none 0.29 60deg)</div>
   <div class="oklch-hue-none">oklch(75 75% none)</div>
   <div class="oklch-with-alpha">oklch(85 0.12 75deg / 0.8)</div>
</body>
</html>
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