CSS Measurements

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CSS supports a number of measurements including absolute units such as inches, centimeters, points, and so on, as well as relative measures such as percentages and em units. Table B-2 summarizes these units of measure.

Table B-2: CSS1 and CSS2 Length Measurement Units

Measurement	Description	Example
%	Defines a measurement as a percentage relative to another value, typically an enclosing element.	p {font- size : 14pt; line-height: 150%;}
cm	Defines a measurement in centimeters.	div {margin-bottom: 1cm;}
em	A relative measurement for the height of a font in em spaces. Because an em unit is equivalent to the size of a given font, if you assign a font to 12pt, each ' em ' unit would be 12pt; thus, 2em would be 24pt.	p { letter-spacing : 5em;}
ex	This value defines a measurement relative to a font's x-height. The x-height is determined by the height of the font's lowercase letter x .	p {font-size: 14pt; line-height: 2ex;}
in	Defines a measurement in inches.	p {word-spacing: .25in;}
mm	Defines a measurement in millimeters.	p {word-spacing: 12mm;}
pc	Defines a measurement in picas. A pica is equivalent to 12 points; thus, there are 6 picas per inch.	p {font-size: 10pc;}
pt	Defines a measurement in points. A point is defined as 1/72 nd of an inch.	body {font-size: 14pt;}
px	Defines a measurement in screen pixels.	p {padding: 15px;}

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