May 21, 2012 - No more exercises! - Final projects due on May 22, 2012, less than one week

Hexadecimal Numbers on the Web

While you may use other schemes for specifying the RGB values for your colors, hexadecimal used to be the only way. It is good to have an understanding of them since you will often see them in code you are viewing.

Hexadecimal Nomenclature

Aw Hexadecimal, this could be a pain in the ASCII

hexadecimal | heksəˈdes(ə)məl|: adjective in Computing
relating to or using a system of numerical notation that has 16 rather than 10 as its base.

Hexadecimal numbers are base 16 instead of the base 10 that we use in "everday" life (counting change...), so we need more digits. If you always count with your fingers like me, well...

Base 10 intergers go from 0 to 9, all the rest of the numbers are made from combinations of these ten numbers.

Base 16 intergers go from 0 to f, the "numbers" a, b, c, d, e, and f are used after the 9 to give us the extra intergers. All hexadecimal numbers are made from combinations of these sixteen intergers.

Using Hexadecimal Numbers for RGB Colors

When you see a hexidecimal number used for specifying an RGB color on the web, it will always be preceeded by the pound sign/hash symbol or #. This lets the browser know that the next three or six digit number is in hexidecimal and are the red, green, and blue values of the color.

Note that I wrote three or six digits above. Most often, you will see six digits, three is shorthand. With six digits, pairs of numbers indicate the RGB values in redredgreengreenblublue order. Here is the hexadecimal value for pink: #FF6699. Since each of the red, green, and blue values are doubles of the same digit, the shorthand version of the number would be: #F69.

Here are a few examples to give you some ideas.

Hexadecimal Number	Color	Visual Example
#FFFFFF or #FFF	White
#FFFF00 or #FF0	Yellow
#00FFFF or #0FF	Aqua
#008080	Teal
#999999 or #999	Medium Gray
#FFA500	Orange
#FF00FF or #F0F	Fuchsia
#000080	Navy
#000000 or #000	Black

Notice how darker colors tend towards the zeroes and lighter colors towards the "f"s.

Try some of the online color pickers to play with hexadecimal colors.