subdials

Subdials are smaller dials integrated into a watch face that display information beyond the main hours and minutes. Also called auxiliary dials or registers, they are common on mechanical watches and are especially associated with chronographs, but they appear on various complications.

In chronographs, subdials primarily track elapsed time. Typically, one subdial records minutes (often up to 30 or 60 minutes) and another records hours (commonly up to 12). A third subdial may show running seconds for the normal time display. In some designs the central hand is used to measure the chronograph seconds, while a subdial records the running seconds. Beyond timing functions, subdials can display calendar details such as date, day, or month; a moon phase indicator is sometimes presented as a subdial; other examples include power reserve indicators and dual time zones.

Layout and design vary widely. Subdials are commonly placed at the 3, 6, and 9 o’clock positions, but arrangements at 12 o’clock or elsewhere are not unusual. They can be perfectly round, square, or oval, and may be recessed or slightly elevated for legibility. The appearance of subdials—size, contrast, and hand style—affects the overall readability of the dial and the aesthetic of the watch.

Subdials emerged as a practical solution for adding timekeeping and calendar functions without enlarging the main dial. They became particularly prominent with the development of wrist chronographs in the early 20th century and remain a defining feature of many classic and modern watches.