Making Those Letters Legible

How to optimize channel letter layout for positive results

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You just completed a site survey for a new channel letter sign. The signage environment is crowded and competitive. Your client wants to know how you can make their sign “stand out and be clear.” What do you say?

This article provides some answers to that question. It briefly reviews some of the “critical factors” that help improve channel letter legibility, clarity and visibility. A sign receives a very brief communication window-and missing that short period means a lost business opportunity. Many of these effectiveness principles apply to other signage types as well.

Letter Case

The initial legibility factor is the letter case. Is your client requesting a sign that has ALL CAPITAL LETTERS? If so, the sign will probably have a lower legibility level than a sign with mixed case lettering (both upper and lower case letters).

Why does using ALL CAPITAL LETTERS make a sign less legible? As stated in a signage industry reference book, “The reason is that portions of the letter that extend above or below the main letter body give many words a recognizable profile or shape, even when the reader is unable to bring the actual word into clear focus. This is particularly important when a sign is to be read from a distance. Upper case words have little or no distinctive variations from a distance, while lower case letter create recognizable shapes even when blurred.”(1)

One industry source estimates that signage using mixed case text is about 15 percent easier to read than signs with upper case text only.

This basic principle applies even when a font that is typically legible has been chosen by your client. Again, your objective is a sign that can be read easily and quickly. Why jeopardize that goal by using ALL CAPITAL LETTERS?


The sign’s font also has a substantial legibility influence. As a brief working definition, legibility is the degree to which a chosen typeface makes it possible for a reader to comprehend a sign’s wording without effort. In other words, a highly legible sign requires no mental “translation” to understand the message.

In contrast, this is compared to a font’s readability. Readability measures how well a given combination of words is read within a larger body of text. Whereas sans serif fonts tend to have a higher degree of legibility, serif fonts tend to have a greater level of readability.

One simple method to assist with this legibility objective is to use a sans serif font in your client’s sign. Research conducted at the University of Cincinnati supports this point. In this study, Dr. James Kellaris listed “a fancy font” as one of the factors that has the potential to cause signage communication failure.(2)

A few legible sans serif fonts are:

  • Arial
  • Calibri
  • Century Gothic
  • Verdana

For channel letters, there is an additional reason for not using an “artistic” font. Letter designs featuring serifs and/or artistic ornamentation will sometimes have channels that are too small for optimal illumination (LED) placement. So the channel letter font choice may also impact the illumination quality.

Reading Distance

Another legibility factor is the typical reading distance for the channel letter sign. This is another important feature in the sign effectiveness equation as it influences the size of the letters necessary for optimal performance.

In this context, “reading distance” means the typical distance from which the sign will be read. Obviously, many signs are read from varying distances. But most signs have a typical range of reading distance-and that is the number you should review with your customer in the chart below. If the design specifies a letter size that is smaller than optimal (The “Maximum Impact” distance is always a safe bet), you need to point that out and ask them to consider larger letters.

The chart below shows the letter sizes needed for varying reading distances.

Clearly, these reading distances are also influenced by the design, font and color layout of the sign (among other variables.) A poor choice on any one of these variables may decrease the readable distance.

Last, mobility is an additional reading distance variable. Business signs are often read from a moving vehicle. This scenario places an even higher premium on fast and easy sign legibility.

Graphic Images and Signage Clarity

Another option for optimal signage performance is the addition of a graphic image. For channel letters, this additional feature is often called a “logo box.” Current signage production technology gives this option very compelling communication potential-the color, design and shape possibilities are endless.

This point is also supported by research. The previously referenced study at the University of Cincinnati included a question about signage aesthetics and layout. The majority of respondents preferred a sign that included both wording and graphic images.(3) The survey statement was:

“I prefer signs that use a combination of words and non-verbal symbols or icons.”

The response breakdown was:

47.9 percent Agree

44.2 percent Neutral

7.9 percent Disagree

In addition, a graphic image may assist with signage clarity, which is always a desirable feature. An image which is closely related to the primary business activity will increase the consumer’s ability to quickly understand the business function.

Channel Letter Sign with Logo Box

Last, a compelling graphic image can be particularly important when the sign is placed in a crowded visual environment-it decreases the chance of signage communication failure.

Day/Night Sign Appearance

Another optimal performance item is the daytime channel letter visibility vs. the night. Some letter configurations have strong day legibility but are less effective at night (and vice versa).

This is sometimes due to the sign having the same face color both day and night. For example, blue may be an excellent day color but not the most visible night color.

One potential solution to this situation is the usage of day/night vinyl on the letter faces (also known as perforated vinyl.) This product permits a sign to have a different day/night color appearance.

For example, note the strong appearance of the First Abilene letters by day, but then note how they are also clear at night in the photos below.

These letters are effective in both environments. The day letter appearance has a strong contrast to the building façade and is easily legible. At night, the white letters are clearly visible. The final clarity touch is the illuminated logo box which states the business type.

Illumination Quality

Bright and even letter face illumination is another important factor for optimal performance and legibility. Several differing issues may impact the illumination quality.


Dim illumination makes a letter sign far less effective. Dimness may be caused by low quality LEDs, an inadequate number of LED strokes or illumination that is simply too old and has lost its brightness.

Sign dimness may have another negative consequence. A poorly lit channel letter set insinuates a business that is poorly run, mismanaged and/or neglected. That can impact a consumer’s quality perception of a business-which in turn can lead to fewer new customers.

Tiger Striping

Tiger striping (or hot spots) is another potential channel letter illumination issue. A tiger stripe occurs when one part of a channel letter face is visibly brighter than an adjacent area.

Just as with overall dimness, tiger striping can make a channel letter sign less legible and less effective. Using a program such as LED Wizard from Aries Graphics can help you install your LEDs in a way that will avoid this issue.

Unlit Letter or Word

A more serious illumination issue occurs when an entire letter (or word) on a channel letter set is unlit. This may render a sign completely illegible at night.

Face Color

The face color is another important legibility factor. When making a face color choice, the initial item to review is the building façade color. Which color(s) will create a strong daytime contrast?

As a general principle, a face color choice that is a similar shade as the building façade is a mistake. That can lead to a far lower legibility level. Select a color with a strong building façade contrast.


Letter kerning is another item with legibility influence. Kerning measures the distance between letters in a word.

This is another area where artistic design can override common sense. If your client’s sign design has a “creative” kerning approach (such as exaggerated spacing between letters), you need to tell them that may have a negative impact on the sign’s overall effectiveness.

High Legibility = Channel Letter Effectiveness

In summary, all of these layout factors exert an influence on the legibility and overall effectiveness of a channel letter set. Use these principles to produce a highly visible and readable channel letter sign-it will mean better results for your client.


1. Charles R. Taylor, Thomas A. Claus and Susan L. Claus, On-Premise Signs as Storefront Marketing Devices and Systems, (The Signage Foundation, P.O. Box 30, South Bend, IN 46624) 9.8 and 9.9.

2. Kellaris, James J. “100,000 Shoppers Can’t Be Wrong: Signage Communication Evidence from the BrandSpark International Grocery Shopper Survey.” The Science of Signage: Proceedings of the National Signage Research and Education Conference, Signage Foundation Inc., Cincinnati, October 12-13, 2011.

3. Ibid.

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John Baylis

John Baylis is the Marketing Manager at Direct Sign Wholesale, a wholesale channel letter manufacturer located in Denver, Colo. Contact John at jb@directsignwholesale.com, or visit Direct Sign Wholesale's website at www.directsignwholesale.com.

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