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| Legibility Guidelines |
|
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| Legibility depends upon many factors,
including lighting, angle, type font and visual acuity. The
ANSI sign standards are based on a ratio of letter height to
reading distance. For signs seen under good lighting conditions,
the ratio is 1 inch of letter height for the sign per 25 feet
of viewing distance. For signs seen under less than favorable
conditions, the ratio drops to 1" for 11.9 feet. |
 |
| Capital
Letter Height of Warning Text |
|
Reading
Distance (ft) |
| Size (inches) |
 |
Good Conditions |
|
Unfavorable
Conditions |
| 0.17 |
|
4.2 |
|
2.0 |
| 0.19 |
|
4.9 |
|
2.3 |
| 0.22 |
|
5.6 |
|
2.6 |
| 0.25 |
|
6.3 |
|
3.0 |
| 0.28 |
|
6.9 |
|
3.3 |
| 0.31 |
|
7.6 |
|
3.6 |
| 0.33 |
|
8.3 |
|
4.0 |
| 0.42 |
|
10.4 |
|
5.0 |
| 0.50 |
|
12.5 |
|
6.0 |
| 0.67 |
|
16.7 |
|
7.9 |
| 0.83 |
|
20.8 |
|
9.9 |
| 1.00 |
|
25.0 |
|
11.9 |
| 1.11 |
|
27.8 |
|
13.2 |
| 1.25 |
|
31.3 |
|
14.9 |
| 1.39 |
|
34.7 |
|
16.5 |
| 1.74 |
|
43.4 |
|
20.7 |
| 2.08 |
|
52.1 |
|
24.8 |
| 2.43 |
|
60.8 |
|
28.9 |
| 2.78 |
|
69.4 |
|
33.1 |
| 3.47 |
|
86.8 |
|
41.3 |
| 4.17 |
|
104.2 |
|
49.6 |
 |
|
|
| Please note that a formatted sign
with the selected letter size for the word messages is best
examined in the environment expected for actual use. Testing
legibility in the intended environment by the persons representative
of the expected viewers certainly offers the greatest assurance
of legibility. |
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