| The premier quality of an effective sign is readability. If a sign cannot be read sufficiently from a distance to allow time to read it, then the message it carries is silenced. |
| Leter Requirements: This table determines which size letters allow good visibility at varying distances. Keep in mind, block letters can be read from a greater distance than script letters. The table gives examples of block letter readability.Readability may vary 10% depending on various color combinations. For the best results use black or red on a white background.As a general rule the Greatest Impact Readable Distance is 10 feet for every 1 inch of letter height. |
| Read Time: From years of study, it has been determined that the recommended minimum reading time is 5 seconds. |
| The times in seconds are calculated assuming a 1" letter to be readable at 50 feet. Each 1" increase results in an additional 50 foot readability. |
| The chart to the right also assumes free flowing traffic. Traffic lights, stop signs, and other conditions can, in some cases, justify smaller character heights. |
| Remember, the figures in the chart represent the time from which letters first become readable until one passes by the sign. They are the maximum. The need to monitor traffic conditions, and standard driving concerns restrict the amount of time a driver can dedicate to reading your message. The answer is to allow the driver more time to read the message through larger letter sizes. |
|
- Maximum Viewing Distance
- in Feet
|
Readable Distance For Maximum Impact in Feet |
- Minimum Required Letter
- Height in Inches
|
| 100 |
40 |
4" |
| 200 |
60 |
6" |
| 350 (city block) |
80 |
8" |
| 450 |
100 |
10" |
| 525 |
120 |
12" |
| 630 |
150 |
15" |
| 750 |
180 |
18" |
| 1,000 |
240 |
24" |
| 1,320 (1/4 mile) |
320 |
32" |
| 1,550 |
360 (city block) |
36" |
|
| |
- Duration of Readability
- (Time in Seconds)
|
| M.P.H. |
4" |
6" |
8" |
10" |
| 25 |
5.5 |
8.2 |
10.9 |
13.6 |
| 35 |
3.9 |
5.8 |
7.8 |
9.7 |
| 45 |
3.0 |
4.5 |
6.1 |
7.6 |
| 55 |
2.5 |
3.7 |
5.0 |
6.2 |
| 65 |
2.1 |
3.1 |
4.5 |
5.7 |
|
|
