What Is a Tachymeter? How to Read and Use a Watch Tachymeter
A tachymeter is a scale on a watch dial or bezel that converts elapsed seconds into a rate per hour. Used with a chronograph (a stopwatch function), it most often shows average speed over a known distance. For example, if it takes 30 seconds to travel 1 kilometer, the tachymeter reads 120—meaning 120 kilometers per…