Font size/Character height [font]

Description

Font size can be characterized in several ways: height of uppercase characters, x-height, type size, type width, height-to-width ratio, and visual angle. Figure 1 gives a visual explanation for some of the ways that font size can be characterized. The height of upper-case characters consists of the measure from the top to the baseline of a capital letter (e.g. the letter X). The x-height consists of the measure from the top to the baseline of a lower-case 'x'. The type size (Lee, 1979), which is most often measured in points (1 pt = 1/72"), consists of the measure from the top of the ascenders to the bottom of descenders and should included the lowest and highest points of in an alphabet. The type width consists of the measure from one side to the other side of a character. Since all characters in the alphabet have different widths (e.g. 'i' compared to 'x'), the average for all letters of the alphabet is taken. The height-to-width ratio consists of the ratio between the height and the width of a character. Often, to calculate this ratio, upper-case letters are used (Levitan et al., 1998).

Figure 1: Font size

The visual angle is the angle that a character forms based on the viewing distance. A character with a fixed height will have a different visual angle depending on the viewing distance (see Figure 2). The formula for the visual angle is (Sanders, 1993):

Where H is the height of a stimulus or detail, and D is the distance from the eye. H and D must be in the same units, such as inches, feet, millimeters, etc.

Figure 2: Visual angle (VA)

Importance

Identifying minimum font size and character size for text will aid designers in developing Universally Designed signs.

Related Guidelines

Products

• Computer and electronic displays (CRT, LCD and electronic display device)
• Permanent building signage
• Print
• Tactile signs
• Warnings on products

Infrastructure

• Highway and street signage

Research and Development Needs

References

Bringhurst, Robert (2004) The Elements of Typographic Style. Vancouver, B.C., Canada: Hartley & Marks, Publishers.

Lee, Marshall. 1979. Bookmaking: The illustrated guide to design/production/editing. New York: R. R. Bowler Company.

Levitan, Lee , Max Bunus, Wende L. Dewing, William F. Reinhart, Pawan Vora, and Robert E. Llaneras. 1998. Preliminary human factors guidelines for automated highway system designers.

Sanders, Mark S. 1993. Human factors in engineering and design. Edited by Mark S. Sanders and Ernest J. McCormick. New York: McGraw-Hill.

Links

Author

• Caroline Joseph, M.A.Sc.
• Beth Tauke, M.A., M.F.A.
• Edward H. Steinfeld, Arch.D., AIA

Editorial Board Review Status

"In Development"