From RationalWiki
Jump to navigation Jump to search

Color on computer screens is made up of 3 "primary" colors: red, green and blue.
You will often see this referred to as "RGB." These colors are "additive": zero of all three gives black, while maximum of all three makes white.[1]

Colors by number[edit]

Computers work with powers of two. The relevant vocabulary for describing colors uses "hexadecimal", which is base sixteen. Hexadecimal numbers are how geeks count up to 15 without using more than one digit. In hexadecimal, 0-15 is counted 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F.

  • Using one hex digit for each of the three base colors, the range for each is 0 to 15 (16 or 24 possibilities), for a total of 163, or 4,096 possible values.
  • Using two hex digits for each color, the range for each is 0 to 255 (256 or 28 possibilities). This yields a total of 2563, or 16,777,216 values;
    Each base color (red, green, and blue) can have a value in one of these ranges.

In HTML, hexadecimal color codes are preceded by "#". Then:

  • Using the 0-15 method, a RGB color is represented as #000 for black, through #FFF for white.
  • In the 0-255 method, black is #000000 and white is #FFFFFF.

Note that equal amounts of red, green and blue produce various shades of gray (for example #A2A2A2). Pure reds are of the form #XX0000, (where X is one of the valid hexidecimal digits 0-F), pure greens are #00XX00, and pure blue shades are #0000XX. Any color combination can be created using any number from 00 to FF in each of the three positions.

Colors by name[edit]

As with many tricks and tools on computers, copying something you like is often the quickest way to get there. There are also palettes of named colors.

Hexadecimal Color
Hexadecimal Color
Hexadecimal Color
aqua #00FFFF Sample text on black black #000000 Sample text blue #0000FF Sample text fuchsia #FF00FF Sample text
gray #808080 Sample text green #008000 Sample text lime #00FF00 Sample text on black maroon #800000 Sample text
navy #000080 Sample text olive #808000 Sample text purple #800080 Sample text red #FF0000 Sample text
silver #C0C0C0 Sample text on black teal #008080 Sample text white #FFFFFF Sample text on black yellow #FFFF00 Sample text on black

If you're really lazy then a list of color templates can be found here.

There is another palette of named colors which might or might not work with various web browsers.

Color picker[edit]

There are plenty of hex color pickers online.

Text color coding[edit]

Using CSS color attribute: <span style="color:</nowiki>''hex triplet or colour name''<nowiki>">text</span>

<span style="color:red">red writing</span>
red writing
<p style="color:#0F0">green writing</p>

green writing

<span style="color:#0000FF">blue writing</span>
blue writing

This has the advantage that other attributes can be included in the same "span" tag.[2]


The use of the <font color> </font> HTML tags can still be used but deprecated. It is not recommended to use <font color> as the feature can be removed at any time.

<font color="red">RED TEXT</font>
<font color="#0F0">GREEN TEXT</font>
<font color="#0000FF">BLUE TEXT</font>

Other use of colors[edit]

Colors can also be defined in other html tags, such as table tags. BGCOLOR="#abcxyz" will set the background color of a table, row, or cell when used inside the appropriate tag. Wiki table colors can also be defined using the "style" attribute.


Please be aware that some readers with poor eyesight cannot read text with a low color contrast. It is recommended to use a tool such as Are my colors accessible? to check whether people can actually read the text.

This text is hard to read isn't it. Imagine if you had you read all the articles like this. It wouldn't be fun at all.

This text is much better to read. You can easily see the words.

External links[edit]


  1. In printing, four colours are used: cyan, magenta, yellow and black (yes, black's not really a color but that's the way it goes) referred to as "CMYK"; these are "subtractive": zero of all four gives white while maximum of all four (or maximum of all 3 colors, or just maximum of black) gives black)
  2. You might like to follow up by reading about Cascading Style Sheets in Wikipedia.

See also[edit]