## Red, Green and Blue

Hexadecimal numbers are used on web pages to set colors.

The color is defined by its mix of Red, Green and Blue, each of which can be in the range:

 0 to 255 (in decimal) , or 00 to FF (in hexadecimal)

 A color can be made by mixing Red, Green and Blue, so it is called the "RGB Color System". It is also called an "Additive" color system, because it starts at black, and then color is added.

## Color Mixer

Try mixing your own colors to see how it works (or type values into the hexadecimal or decimal boxes):

Also see Interactive Color Wheel.

Hexadecimal numbers are "natural" to computers, because computers store and handle binary digits, and four binary digits make one hexadecimal digit (see Binary Digits):

0 0 0
1 1 1
2 10 2
3 11 3
4 100 4
5 101 5
6 110 6
7 111 7
8 1000 8
9 1001 9
10 1010 A
11 1011 B
12 1100 C
13 1101 D
14 1110 E
15 1111 F

So one hexadecimal digit can have 16 different values (0 to 15 in decimal), and two hexadecimal digits together (called a "byte") can make 16×16=256 different levels of color.

## 16 Million Colors

Because each of the three colors can have values from 0 to 255 (256 possible values), there are:

 256 × 256 × 256 = 2563 = 16,777,216 possible color combinations

(and this is why you see claims of "16 Million Colors" on computer equipment)

## Web Format

The format ("notation") used on web pages is #RRGGBB, where RR is how much Red (using two hexadecimal digits), GG is how much Green, and BB how much Blue.

• 64/255 Red,
• 48/255 Green
• 255/255 (i.e. full) Blue

So it is (64,48,255) in decimal, which is equal to (40,30,FF) in hexadecimal and is coded as #4030FF.