<hue>

A <hue> can be either an <angle> or a <number>.

<angle>

An angle expressed in degrees, gradians, radians, or turns using the deg, grad, rad, or turn, respectively.

<number>

A real number, representing degrees of the hue angle.

As an <angle> is periodic, <hue> is normalized to the range [0deg, 360deg). It implicitly wraps around such that 480deg is the same as 120deg, -120deg is the same as 240deg, -1turn is the same as 1turn, and so on.

The color wheel above shows hues at all angles in the sRGB color space. In particular, red is at 0deg, yellow is at 60deg, lime is at 120deg, cyan is at 180deg, blue is at 240deg, and magenta is at 300deg.

The angles corresponding to particular hues differ depending on the color space. For example, the hue angle of sRGB green is 120deg in the sRGB color space, but 134.39deg in the CIELAB color space.

The following table lists typical colors at various angles in the sRGB (used by hsl() and hwb()), CIELAB (used by lch()), and Oklab (used by oklch()) color spaces:

<hue> values are interpolated as <angle> values, and the default interpolation algorithm is shorter. In some color-related CSS functions, this can be overridden by the <hue-interpolation-method> component.

<hue> = 
  <number>  |
  <angle>   

The following example shows the effect of changing the hue value of the hsl() functional notation on a color.

HTML

<input type="range" min="0" max="360" value="0" id="hue-slider" />
<p>Hue: <span id="hue-value">0deg</span></p>
<div id="box"></div>

CSS

div {
  width: 100px;
  height: 100px;
  margin: 10px;
  border: 1px solid black;
}
p {
  font-family: sans-serif;
}
span {
  font-family: monospace;
  background: rgb(0 0 0 / 10%);
  padding: 3px;
}
#hue-slider {
  width: 90%;
}

#box {
  background-color: hsl(0 100% 50%);
}

JavaScript

const hue = document.querySelector("#hue-slider");
const box = document.querySelector("#box");
hue.addEventListener("input", () => {
  box.style.backgroundColor = `hsl(${hue.value} 100% 50%)`;
  document.querySelector("#hue-value").textContent = `${hue.value}deg`;
});

Result

The following example shows a similar red color in different color spaces. The values in the lch() and oklch() functions are rounded for readability.

HTML

<div data-color="hsl-red">hsl()</div>
<div data-color="hwb-red">hwb()</div>
<div data-color="lch-red">lch()</div>
<div data-color="oklch-red">oklch()</div>

CSS

[data-color="hsl-red"] {
  /* hsl(<hue> <saturation> <lightness>) */
  background-color: hsl(0 100% 50%);
}
[data-color="hwb-red"] {
  /* hwb(<hue> <whiteness> <blackness>) */
  background-color: hwb(0 0% 0%);
}
[data-color="lch-red"] {
  /* lch(<lightness> <chroma> <hue>) */
  background-color: lch(50 150 40);
}
[data-color="oklch-red"] {
  /* oklch(<lightness> <chroma> <hue>) */
  background-color: oklch(0.6 0.4 20);
}

div {
  font-family: monospace;
  width: 100px;
  height: 100px;
  margin: 10px;
  border: 1px solid black;
  display: inline-block;
}

Result

• <color>
• <hue-interpolation-method>