A tachometer is one of the functions of chronographs generally marked on a chronograph watch to calculate speed or production rates over a given distance or time. It works by using a scale usually marked on the bezel or the dial for converting elapsed time into units per hour. For example, using a tachometer to measure how long it takes a car to travel one mile will indicate the speed of the car in miles per hour.
The tachometer is therefore viewed by motorsport enthusiasts and professionals as a practical device. Other than its practical use, the tachometer also gives the watch a dynamic and sporty feel, showing its connection to the high-performance environment.
