The primary functions of the sub-dials on a chronograph watch vary depending on the specific model, but the most common ones include:
Stopwatch: One of the sub-dials is dedicated to tracking elapsed time. It typically measures seconds, minutes, and sometimes hours. This function allows users to time events or activities precisely.
Tachymeter: Another sub-dial often found on chronograph watches is a tachymeter. It enables users to measure speed based on a fixed distance. By starting the chronograph when an object passes a specific point and stopping it when the object reaches another point, users can determine its speed using the tachymeter scale.
Sub-seconds: Some chronograph watches incorporate a sub-dial to display continuous seconds, separate from the main timekeeping function. It provides a more precise reading of seconds, especially when the watch is being used as a stopwatch.
Dual time zone: In certain chronograph watches designed for travelers or international users, a sub-dial may indicate a second time zone. This feature allows wearers to easily keep track of time in two different regions simultaneously.