Visibility of analog clock displays and the distances that they can be seen is a very subjective matter. In addition, other factors associated with the specific installation must be considered. In particular the viewer's eyesight, clock diameter, and ambient light are the most important. We offer this discussion as a guide for helping estimate the size that may be required for a particular application.
Masterclock offers analog clock displays with diameter sizes ranging from 12"-30cm to 30"-76cm in size.
A guide, when deciding which size clock is best, is 6"-15cm of diameter for every 50 feet (15 meters) of viewing distance.
Therefore, a 12"–30 cm diameter display could be considered for distance up 100´-30m,
a 18"-46cm display for distances of 150´-46m, etc.
Consider however, that at these distances, a person would have to stop and concentrate to see the displays.
If the user needs to know the time by simply glancing at the clock,
the distance to size ratio should be cut (at least) in half.
Therefore, if a person were to glance at a clock from 50' (15m) away,
they would need a 12" (30cm) display, at 100' (30m) they would need a 18" (46cm) or perhaps a 30" (76cm) display, and so forth.
These distance estimates will be severely compromised by ambient light conditions.
If the application is critical we suggest that you experiment with printed faces,
or better, a sample display, and verify which size is adequate for your application.
| Face Diameter | Maximum Viewing Distance | Typical Viewing Distance |
| 12" (30cm) | 100' (30m) | 50' (15m) |
| 18" (46cm) | 150' (46m) | 75' (23m) |
| 30" (76cm) | 250' (76m) | 125' (38m) |
