Letter size on signs

How Big You Should Make your Lettering on a Sign

The term "Highway Gothic" is a reference to the standard typefaces used in traffic signs. Even the FHWA (Federal Highway Administration) sometimes refers to their typefaces in that manner. The official terms for the typefaces are "FHWA Series B" and "FHWA Series C", etc. The normal typefaces used for most signs are the Series B through F. Series B has the narrowest letters, such as the word "PARKING" on a No Parking sign. Series F is not often used and it contains the widest letters pursuant to a particular height. The widest letters may be used when it is necessary for a sign to be seen from a long distance. For many years, Series B, C, D, E and F typefaces included capital letters only, but in 2004 the FWHA approved lower-case letters for such typefaces. There have been changes recently to the MUTCD (Manual on Uniform Traffic Control Devices) whereby lower-case legends for guide signs on all roadways have been approved. The lower case height is 75% of the upper case height. As an example, a lower case "s" is 75% of the height of an upper case "S". The large signs seen on freeways and expressways normally use Series E with modified upper and lower case letters. The guide signs on traditional roads utilize typefaces from Series C to Series E Modified while taking into consideration the sign width and desired legibility distance.

Series E Modified includes the word "modified" because the width of lines making up letters (letter stroke) is modified to be 20% of the letter height. Series B through Series F letters use a stroke width which is roughly 13-18% of the height.

A type of lettering known by its generic term of "button copy" has been used for decades throughout the country on large freeway and expressway signs. Button copy is actually the characters of highway signs which are constructed from enameled metal with small white round reflectors known as "buttons" and inlaid at the surface to provide retroreflectivity in the dark of night. There are newer computer cut reflective sign letters used today; therefore, button copy is no longer manufactured in the United States, as it was too costly to produce. The last state to use button copy sign letters was Arizona, but it stopped ordering new button copy signs in 2000. FHWA Series D,E, and Series E Modified typefaces are similar in appearance to button copy typefaces, with minor variations for the inlaid reflectors.

Clearview is another typeface being developed for highway signs. It was authorized by the FHWA for use on guide signs and other signs whereby the lettering is lighter than the background of the sign. It has shown positive results in ease of legibility.

A font known as Clarendon is used by the National Park Service. For most drivers, this font rates much the same as the Series E modified in terms of legibility.

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Letter Sizes