Specifying Size

In several situations you may need to specify the size of an element on screen, whether it is the width of a table, the size of a font or the width of a textbox. There are several ways of specifying size, but care must be taken to ensure that the sizing method does not hinder any accessibility aids. The main sizing methods are:

  • Relative, measured in pixels (e.g. 100px)
  • Relative to a reference length, measured in percent (e.g. 50%)
  • Absolute, measured in points (1pt = 1/72 of an inch) (e.g. 12pt) or picas (1pica = 1/6 of an inch)
  • Relative to the parents font height measured in em (e.g. 1.5em is 1.5 times the parents font height).

Absolute measurements in inches, centimetres and millimetres are supported, but all absolute sizing values are only of use when you know the exact size of the device, e.g. for printing.

See a demonstration of all the above elements in page SizeExample.aspx.

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