2013 California Standards for Accessible Design Pocket Guide

11B-703.2.5 Character height.

Character height measured vertically from the baseline of the character shall be ⁵/₈ inch (15.9 mm) minimum and 2 inches (51 mm) maximum based on the height of the uppercase letter “I”. 

Exception:  Reserved

[2010 ADAS] EXCEPTION:  Where separate raised and visual characters with the same information are provided, raised character height shall be permitted to be ½ inch (13 mm) minimum.

FIGURE 11B-703.2.5

HEIGHT OF RAISED CHARACTERS