Visibility of Analog Clocks

Face Diameter Maximum Viewing Distance Typical Viewing Distance
12 in
(30 cm)
100 ft
(30 m)
50 ft
(15 m)
15 in
(38 cm)
125 ft
(38 m)
63 ft
(19 m)
18 in
(46 cm)
150 ft
(46 m)
75 ft
(23 m)

The visibility of analog clock displays and the distances they can be seen from is a very subjective matter often based on a viewer's eyesight and the ambient light, which vary by person and time or day.

Masterclock offers analog clock displays with diameter sizes ranging from 12 to 30 inches (30 to 76 cm) in size. When deciding which size clock is best, estimate 6 inches (15 cm) of clock-face diameter for every 50 feet (15 m) of viewing distance. Therefore, a 12-inch (30 cm) diameter display could be considered for viewing distances up 100 feet (30 m). An 18-inch (46 cm) display would be better for distances of 150 feet (46 m), etc. 

Consider 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  in half. If a person were to glance at a clock from 50 feet (15 m) away, they would need a 12-inch (30 cm) display, but at 100 feet (30 m) they would need an 18-inch (46 cm) clock-face or larger. 

These distance estimates could be severely compromised by adverse light conditions. If the application is critical we suggest that you experiment with printed faces, or better yet a sample display from Masterclock to verify the best size for your application.