hsl()

The hsl() functional notation expresses an sRGB color according to its hue, saturation, and lightness components. An optional alpha component represents the color's transparency.

Defining complementary colors with hsl() can be done with a single formula, as they are positioned on the same diameter of the color wheel. If theta is the angle of a color, its complementary one will have 180deg-theta as its hue coordinate.

Syntax

/* Syntax with space-separated values */
hsl(hue saturation lightness)
hsl(hue saturation lightness / alpha)

/* Syntax with comma-separated values */
hsl(hue, saturation, lightness)
hsl(hue, saturation, lightness, alpha)

Values

hue

An <angle> of the color wheel given in one of the following units: deg, rad, grad, or turn. When written as a unitless <number>, it is interpreted as degrees. By definition, red is 0deg, with the other colors spread around the circle, so green is 120deg, blue is 240deg, etc. As an <angle> is periodic, it implicitly wraps around such that -120deg = 240deg, 480deg = 120deg, -1turn = 1turn, and so on. This color wheel helps finding the angle associated with a color: A color wheel indicating the angle for the hue of the primary (red-green-blue) and secondary (yellow-cyan-magenta) colors

saturation

A <percentage> where 100% is completely saturated, while 0% is completely unsaturated (gray).

lightness

A <percentage> where 100% is white, 0% is black, and 50% is "normal".

alpha Optional

A <percentage> or a <number> between 0 and 1, where the number 1 corresponds to 100% and means full opacity, while 0 corresponds to 0% and means fully transparent.

Examples

The hsl() function works well with conic-gradient() as both deal with angles.

div {
  width: 100px;
  height: 100px;
  background: conic-gradient(
    hsl(360, 100%, 50%),
    hsl(315, 100%, 50%),
    hsl(270, 100%, 50%),
    hsl(225, 100%, 50%),
    hsl(180, 100%, 50%),
    hsl(135, 100%, 50%),
    hsl(90, 100%, 50%),
    hsl(45, 100%, 50%),
    hsl(0, 100%, 50%)
  );
  clip-path: circle(closest-side);
}

Specifications

Specification
CSS Color Module Level 4
# the-hsl-notation

Browser compatibility

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See also