Hexadecimal Colors
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) |
 |
Because 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):
Hexadecimals
Hexadecimal numbers are "natural" to computers, because computers store and handle binary digits, and four binary digits make one hexadecimal digit (see Binary Digits):
| Decimal: | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Binary: | 0 | 1 | 10 | 11 | 100 | 101 | 110 | 111 | 1000 | 1001 | 1010 | 1011 | 1100 | 1101 | 1110 | 1111 |
| Hexadecimal: | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | A | B | C | D | E | F |
Two Hexadecimal digits together (called a "byte" in computer terminology) can represent 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 specifies the value of the Red component of the color (using two hexadecimal digits), GG the Green component and BB the Blue component.
Example: a shade of blue is made up of:
- 64/255 Red,
- 48/255 Green
- 255/255 (i.e. full) Blue
So it is (64,48,255) in decimal, which is equivalent to (40,30,FF) in hexadecimal and would be coded as #4030FF.
This may help you remember:
Roses are #FF0000
Violets are #0000FF
Just don't forget,
Grass is #00FF00, too
Some Common Colors
| Color |
Decimal (Red, Green, Blue) |
Hexadecimal (#RRGGBB) |
|---|---|---|
| Black | (0, 0, 0) | #000000 |
| White | (255, 255, 255) | #FFFFFF |
| Red | (255, 0, 0) | #FF0000 |
| Green | (0, 255, 0) | #00FF00 |
| Blue | (0, 0, 255) | #0000FF |
| Yellow | (255, 255, 0) | #FFFF00 |
| Cyan | (0, 255, 255) | #00FFFF |
| Magenta | (255, 0, 255) | #FF00FF |
Try entering the hexadecimal code into the color mixer above, and see what you get (you can copy, then right-click the hexadecimal box, and select "paste").
I have also compiled a much longer list of Hexadecimal Colors and their Names.