Watches Lessons in time: how to use a tachymeter

3 min

Demystifying the scale on your watch dial.

TAG Heuer Carrera Chronograph (CBS2210.FC6534)

From the cockpits of vintage aircrafts to the wrists of race car drivers, the tachymeter has consistently proven itself to be a valuable instrument. It’s often mistaken for being just another design element on many chronograph watches. But there’s more to the tachymeter than meets the eye. It has a deep historical significance and remains an essential tool in speed-related sports.

The tachymeter and how to use it

Simply put, a tachymeter is a scale on a watch dial used to determine speed based on time. At its core, a tachymeter is quite straightforward to use. All you have to do is:

  • Start your chronograph when a moving object, like a car, passes a starting point.
  • Stop the chronograph when the object travels a predetermined distance (for example, one mile or one kilometer).
  • The seconds hand will point to a number on the tachymeter scale. This number represents the object’s speed in units per hour (like miles per hour).

If you start timing a car as it passes you and stop the timer when it has traveled one mile, and it took 30 seconds, the seconds hand will point to 120 on the tachymeter scale. This indicates that the car was moving at 120 mph. It looks complicated but it’s really that simple.

A brief history of the tachymeter

The term ‘tachymeter’ comes from the Greek word ‘tachos’, meaning ‘speed,’ and ‘metron’, meaning ‘measure’. Historically, the tachymeter’s primary function was to compute speed based on travel time. This tool was incredibly beneficial for pilots, race car drivers, and even engineers in the early 19th century.

The tachymeter scale was typically etched onto the bezel of a watch or printed on the outer edge of the dial. As technology evolved and speed became more important in various industries, the demand for accurate speed measurement tools grew. This led to the tachymeter’s adoption in more professional and luxury watches.

The relentless pursuit of speed and time

TAG Heuer has always been synonymous with precision and motorsports. And that’s why it has often embraced the tachymeter in many of its designs. From the iconic Carrera collection to the adrenaline-filled Formula 1 range, several TAG Heuer timepieces come with tachymeters.

With its roots deeply embedded in history, the tachymeter stands as a testament to man’s relentless pursuit of speed and precision. While many of us may never use it to measure the blistering pace of a Formula 1 car, its presence on a watch, especially if it’s a TAG Heuer, serves as a nod to an era where even a split second can make all the difference. Whether you’re a watch enthusiast or someone who appreciates the blend of form and function, the tachymeter is a symbol of our timeless fascination with speed.