hwb

HWB stands for Hue, White, and Black and is a color representation that describes colors by three components: a base hue, the amount of white to mix with that hue, and the amount of black to mix in. The hue determines the color family, while whiteness and blackness adjust lightness and saturation by diluting the base hue with white and black.

In CSS Color Module Level 4, hwb() is a functional notation that specifies a color as hwb(h w% b%), where h is the hue angle in degrees (0–360), and w and b are whiteness and blackness given as percentages (0–100%). The resulting color is a mixture of the pure hue with white and with black, allowing direct control over tint and shade without adjusting saturation or lightness separately.

HWB is related to HSL and HSV in that they share the concept of a hue component, but HWB expresses lightness through white and black mixing rather than through a separate lightness dimension. Converting between HWB and RGB (or other spaces) requires algorithms that blend the base hue with the specified amounts of white and black, producing a wide range of pastel to deep tones depending on the values chosen.

Usage is primarily in digital color specification and design systems, offering an intuitive way to create tinted or shaded variants by specifying whiteness and blackness directly. Support in web browsers has grown for the hwb() function as part of CSS color capabilities, alongside traditional RGB, HSL, and HSV formats. HWB remains a niche but useful option for designers seeking straightforward color-tint control.