DETERMINING LETTER HEIGHT AND SIGN SIZE
The overall legibility of a sign is essentially determined by the height, color, and font characteristics of the letters making up its message component.
A Sign with 4-inch tall text is best read from around 40 feet away but is still readable from as far as 150 feet.
Note: 15 percent increase in letter height required when all upper case letters (all caps) are used instead of more legible upper and lower case letters with initial caps.
SIMPLIFIED LETTER VISIBILITY CHART