Specifications

Crestron Programming Design Kit
Doc. 5277J | crestron.com
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Font Height (Type Size)
Measurement
When specifying the height of a font and spacing (both vertically and horizontally), the designer should be aware
that there are several scales and methods of measurement. The traditional printer’s “point” used for typesize-height
equals 1/100 of an inch; however, when it is used to measure distance between lines, words, etc., a point is
approximately equal to 1/72 of an inch.
Font Height versus Viewing Condition
Most of the information in the literature regarding font height is presented in graphs. These graphs usually indicate
the relationship between character height, viewing distance, illumination level, stroke width, and visual acuity.
While evaluating type size for optimum reading, an experiment in 1963 reported that a 0.11 inch type size was read
significantly faster than 0.10 inch. The majority of the readers judged the 0.11-inch type size as the most legible.
Stroke widths affect the ability of the eye to differentiate between the stroke of the character (“I”) and the space
inside the character (“E,” F”). The width of a stroke is a function of height of the character. Most human factors data
books recommend the use of a height-to-width ratio of 5:3.
This recommended ratio is applicable only when the document is in front of the observer (a 90 degrees angle
between the line-of-sight and the document). In designing a display that is viewed from an unfavorable viewing
angle (which may artificially reduce the apparent width of the character), a different height-to-width ratio (e.g., 5:4)
should be considered in order to increase the actual width of the character.
The vertical and horizontal spacing between characters affects the legibility and readability of the text especially
when the font height is small. Increasing the vertical spacing between lines reduces the probability of adverse
visual effect from the “pattern of stripes” Research done in 1987 suggests that “judgments of the clarity of text...
are critically dependent on the spacing of the lines, more so than the overall density of lettering. As a result, the
clarity of text can potentially be increased at no extra cost by increasing the separation between the lines slightly
and decreasing slightly the mean horizontal spacing between the centers of letters, within the limits of conventional
typography”. In addition, the “opening” of an appropriate vertical space between lines reduces the chance of optical
bridging between adjacent lines—a critical factor for the design of any list-type display. The recommended vertical
space between lines is 25-33 percent of the overall size of the font. The horizontal space between characters
should not be less than one stroke width. As for word spacing, the gap between characters should be large enough
to allow grouping of words. This is achieved when the word space