Legibility is extremely important when it comes to text in signs. Viewers must be able to easily and quickly read the sign at the intended viewing distance without any strain on their eyes. As such it is important for the text in signs to be sized adequately so that the message reaches the desired audience.
Bigger fonts are recommended for signs that are intended for traffic use. The general rule of thumb is having letters of 1 inch of letter height for every 10 feet of viewing distance.
The formula used for calculating X height in relation to desired reading distance is:
X-height = R/10
Where R= reading distance in feet and X= height in inches
According to professional designers and sign makers, the following traits must be kept in mind when selecting a font family:
- Straightforward and clear type design. It should be sans serif
- Letterforms must be easily recognizable
- Visual appearance must be enhanced through positive letter spacing
- Font Family is a package of a number of different weights not a lot of different fonts
- Good readability is ensured by a large X-height for the typeface
Points to note
The typeface must be evaluated first. In case you employ a face which is designed for signage, the above parameters can be applied. However, if the typography is a component of a bigger brand standard, it is an excellent idea to do some research.
The X-height best indicates legibility. The other attributes contribute to legibility to a smaller degree.
When legibility concerns are taken into account, it is vital to consider distance between the sign and the furthest viewer. You should use this distance as “worst case scenario” and find out how large the sign must be. Extra display area could be required to offer extra space for bigger windows, translating to bigger displays, or extra columns or the rows of signs.
Distance is a major factor in being able to view signs and read the text on them. It is also important to remember the viewing angle and environmental conditions when installing signs. In case of narrow width fonts, the legibility reduces swiftly when you see the sign at an angle. Lighting conditions will influence weight and stroke contrast. The characters’ relative complexity will determine how they will be read when moving.
The objective of any sign is to communicate in an effective manner. That objective can only be achieved if it is easily read. This need has led to the development of multiple readability thumb rules. These rules are now widely used when it comes to selecting font sizes.