### Math Spacing and Length Units

Math spacing:

Lengths defined relative to characters:

 em width of M ex width of x mu 1 mu = 1/18 em

Physical lengths (commonly used):

 mm millimeter cm centimeter in inch 1 in = 25.4 mm pt point 1 pt = 1/72.27 in

Physical lengths (not so commonly used):

 bp big point 1 bp = 1/72 in pc pica 1 pc = 12 pt sp scaled point 1 sp = 1/65536 pt dd didot point 1 dd = 1238/1157 pt cc cicero 1 cc = 12 dd

#### 1 Response to “Math Spacing and Length Units”

1. 1 domj July 11, 2013 at 4:21 am

em and \quad are the same, but they are only approximately the width of M. They are rather defined to be the size of the font, that is 1 em in a 12pt font is exactly 12pt wide.