Bad signage contributes to more people getting lost than a poor sense of direction. Consider the times that you failed to see a sign because it was too small or obscurely placed. Or stood baffled before a directory that was illogically organized and badly lit. In the realm of graphic information, wayfinding systems abide by their own set of rules. Many typefaces that are easy to read on a printed page are frustrating to make out in signage. The same goes for colors. This is why some designers and their clients are chagrined to find that the system that looked so stunning in miniature mock-up failed miserably when installed at actual size. Offered here are a few basic rules of thumb to keep in mind—they all apply to interior signage and viewing in optimum lighting conditions. A recommended source is "Wayfinding: People, Signs and Architecture" by Paul Arthur and Romedi Passini (Focus Strategic Communications Inc.).

Rule of Thumb #1: "X" Height and Reverse Type
Research has shown that the most legible type for signage is black on white, with lower case type having an "x" height that is in a 3:4 ratio with capital letters. When type is reversed, white on black, the letters tend to look 10-12% bolder. A drawback of white-on-black is the optical halo that forms around words. Also, when using these backgrounds in combination, adjust the type so they will look consistent in size.

Rule of Thumb #2: Distance Legibility
Studies have shown that in normal daylight conditions, people with 20/20 vision are able to read a 1-inch-high letter (25mm) from a distance of 50 feet. So, for every additional 50 feet make the letter 1 inch higher. Approaching a sign from an angle can reduce legibility by as much as 30-50%. Combine that with less than perfect eyesight and dim lighting and legibility is diminished further. So, for directional signs many experts recommend upping the ratio to 1.75 inches for every 50 feet.

Rule of Thumb #3: Directories
Information on a wayfinding directory should be limited to six items, which is about as much as a person can take in quickly when walking by. Information should be organized by direction, not listed alphabetically or according to what looks graphically interesting.

Rule of Thumb #4: Color
Wayfinding signs are not the place to feature subtle corporate colors or the latest fashion palette. When using a combination of colors, the higher the contrast the easier the sign can be read.