The Material 3 Expressive color framework uses dynamic color theming, based on
two seed colors mapped on the HCT (Hue, Chroma and Tone) color system.

## Essential terms

Color role
:   Like the "numbers" on a paint-by-number canvas, color roles are assigned to
    specific UI elements. They have names like primary, on primary, and primary
    container. The same color role is used for both light and dark themes. See all
    color roles

HCT
:   HCT stands for hue, chroma, and tone.

## Define colors with hue, chroma, and tone (HCT)

HCT color generator creating a set of color palettes from one seed color to
creates a three-dimensional color model that defines colors based on their hue
(color), chroma (saturation), and tone (lightness)

There are three main accents colors: primary, secondary and tertiary. Neutral
shades, such as various tones of gray with a hint of primary color, are ideal
for use as container colors for rich content due to their monochromatic nature.

### Hue


Hue is the perception of a color, such as red, orange, yellow, green, blue, and
violet. Hue is quantified by a number ranging from 0-360 and is a circular
spectrum (values 0 and 360 are the same hue).  
![](https://developer.android.com/static/wear/images/design/color-hue.png)

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### Chroma


Chroma is how colorful or neutral (gray, black or white) a color appears. Chroma
is quantified by a number ranging from 0 (completely gray, black or white) to
infinity (most vibrant), though chroma values in HCT top out at roughly 120.

Because of biological and screen rendering limitations, different hues and
different tones will have different maximal chroma values.  
![](https://developer.android.com/static/wear/images/design/color-chroma.png)

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### Tone


Tone is how light or dark a color appears. Tone is sometimes also referred to as
*luminance*. Tone is quantified by a number ranging from 0 (pure black, no
luminance) to 100 (pure white, complete luminance).

Tone is crucial for visual accessibility because it determines contrast. Colors
with a greater difference in tone create higher contrast, while those with a
smaller difference create lower contrast.  
![](https://developer.android.com/static/wear/images/design/color-tone.png)

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## Dynamic color (color theming)

Wear OS implements a theming system compliant with [Web Content Accessibility
Guidelines (WCAG)-AAA](https://www.w3.org/TR/WCAG22/#contrast-enhanced), derived from two designated *seed
colors*. Specifically, these seed colors serve as the basis for primary and
tertiary palettes. Using these two initial colors, the system generates a
comprehensive color palette encompassing primary, secondary, tertiary, and
surface palettes. Subsequently, this generated theme is applied across Wear OS
components, System UI elements, tiles, and apps.
![Higher seed values represent colors that are closer to white](https://developer.android.com/static/wear/images/design/color-seed-overview-spectrum.png) Each Watch face defines two seed colors, used for primary and tertiary palettes.

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![](https://developer.android.com/static/wear/images/design/color-seed-algorithm.png) These seeds are put through an algorithm that becomes five tonal ranges, specific tones (based on luminance) are slotted into the predefined roles that consist of a scheme. Colors are mapped to a scheme through design tokens.

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![](https://developer.android.com/static/wear/images/design/color-seed-application.png) Each design token is then applied to the SysUI, tiles and apps that have opted in to using dynamic color.

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Depending on your preference, you can use either a specific seed color or a
brand color to derive your dynamic color.

### From seed color

Dynamic color will automatically create an accessible color scheme based on a
specific seed color.

Because the UI could end up with any number of different source colors, it's
best to initially design using the baseline color scheme so you can ensure the
right color roles are mapped to the right components in your product. Use the
Material Theme Builder to see how your UI mocks look across a range of source
colors and adjust settings as needed.


![](https://developer.android.com/static/wear/images/design/color-palette-seed.png)

Color palette (from Watch face seed colors)  
![](https://developer.android.com/static/wear/images/design/color-theme-seed-tile.png)

Color theme applied to a Tile  
![](https://developer.android.com/static/wear/images/design/color-theme-seed-app.png)

Color theme applied to an app screen

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### From brand color

Similar to the way Material 3 Expressive treats color roles, Wear OS applies
color to individualized experiences with dynamic and accessible color
expression. Wear OS uses only the dark theme because the wearable interface is
built on a black background. Being a platform that runs on touch devices, Wear
OS also has a more limited color palette as it doesn't require as many hover and
focus states. Use the Wear OS-specific color theme building tools to build a
custom theme around your brand and generate the full reference palettes and
assigned color roles that support Material Design tokens and are built to work
seamlessly with system UI components.


![](https://developer.android.com/static/wear/images/design/color-palette-brand.png)

Color palette (from artwork seed colors)  
![](https://developer.android.com/static/wear/images/design/color-theme-brand-tile.png)

Color theme applied to a Tile  
![](https://developer.android.com/static/wear/images/design/color-theme-brand-app.png)

Color theme applied to an app screen

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