Percent color in Android for Material Design

Question

In Google's spec for material design, I see colors specified as percentages:

To convey a hierarchy of information, you can use different shades for text. The standard alpha value for text on a white background is 87% (#000000). Secondary text, which is lower in the visual hierarchy, should have an alpha value of 54% (#000000).

I don't understand how these percentages work. For example, if the background color is white, what is the color of the text?

What if my background were say #607D8B. What would my text color be? Is it just the background color with the opacity (alpha) set to the percentage?

Answer 1

The percentage are for visibility of the color

When we specify any color using hex format :

First 2 digit : visibility

After 6 digit : RRGGBB

So, the calculation example is :

(87)% of (100) decimel = 87 %   ->    convert to (87)% of (256) in hex 222.72 rounding to 223 which is (DF) in hex

So your color code = #DF607D8B -- primary

Same way, any perentage should be converted to hex

You can check table : here