Definition of Em:

  1. Unit of relative distance in typography, one em being equivalent to the point size of the type. In 8 point type, an em is 8 point wide; in 9 point type, 9 point wide; in 10 point type, 10 point wide ... and so on. So named because traditionally it is defined as the width of a capital (uppercase) letter M in the face and point of type being used. See also en.

  2. A unit for measuring the width of printed matter, equal to the height of the type size being used.

How to use Em in a sentence?

  1. From there, sizing descendant elements with ems (a relative unit of measurement) becomes much more logical: 1em is 10 px, 1.6em is 16 px, .9em is 9px, and so forth.

Meaning of Em & Em Definition