CSS Length Units

This section defines the supported length units for CSS Attributes. Unless otherwise specified, the length units are supported as of Microsoft® Internet Explorer version 3 or later. An asterisk (*) indicates the length unit is available as of Internet Explorer version 4 or later.

Relative length units

em ^* The height of the element's font.

ex ^* The height of the letter "x".

px Pixels.

% Percentage.

Absolute length units

in Inches (1 inch = 2.54 centimeters).

cm Centimeters.

mm Millimeters.

pt Points (1 point = 1/72 inches).

pc Picas (1 pica = 12 points).

Relative length units
em ^*	The height of the element's font.
ex ^*	The height of the letter "x".
px	Pixels.
%	Percentage.
Absolute length units
in	Inches (1 inch = 2.54 centimeters).
cm	Centimeters.
mm	Millimeters.
pt	Points (1 point = 1/72 inches).
pc	Picas (1 pica = 12 points).

Measurements and positions in cascading style sheet (CSS) properties are made using length units. Internet Explorer supports two types of length units: relative and absolute.

A relative length unit specifies a length in relation to another length property. Relative length units scale better from one output device to another, such as from a monitor to a printer. Percentages and keywords perform similarly.

An absolute length unit specifies an absolute measurement, such as inches or centimeters. Absolute length units are useful when the physical properties of the output device are known.