What is a tachymeter and how do you use it?

On many chronographs, there is a prominent scale on the outer edge of the dial or on the bezel, marked with numbers ranging from around 60 to 500 – this is known as the tachymeter scale. What may appear to be merely decorative at first glance is, in fact, a practical tool for measuring speed. In this guide, you’ll find out exactly what a tachymeter is, how to read it correctly and in which situations it proves to be a useful tool.

What is a tachymeter?

The term ‘tachymeter’ comes from Ancient Greek: ‘tachýs’ means ‘fast’ and ‘métron’ stands for ‘measure’. In watches, a tachymeter refers to a scale that can be used to determine average speeds over a known distance or to calculate distances when a reference point is available. Unlike a car’s speedometer, which displays speed continuously, a watch’s tachymeter works in conjunction with a chronograph’s stopwatch function.

The scale is calibrated to indicate the number of units per hour, based on the time taken to cover one unit (for example, one kilometre). With numbers ranging from 500 to 60, the tachymeter scale on the watch is easy to recognise. An additional stopwatch function is required for the measurement, which is why many wristwatches with a tachymeter are also equipped as chronographs.

How speed measurement works

The principle is surprisingly simple: you measure the time taken to cover a known distance and then read the speed directly from the scale.

Here’s how to do it step by step:

1. Choose a defined distance, e.g. 1 kilometre
2. Start the seconds hand at the 12 o’clock position as soon as you pass the starting point
3. Stop the hand once you have covered the distance
4. Read the average speed from the position of the stopped seconds hand on the tachymeter scale

Practical example: If the hand stops at 20 seconds, the scale reads 180 → speed: 180 km/h

The maths behind the tachymeter scale

The tachymeter scale is based on a simple formula: 3,600 divided by the number of seconds measured. As there are 3,600 seconds in an hour, for 20 seconds this gives: 3,600 ÷ 20 = 180. This value corresponds to the number of units (kilometres, miles, laps, etc.) per hour.

Most tachymeter scales display values between 60 and 500. This means the measurement is most reliable for time intervals of between approximately 7 and 60 seconds.

The origins of the tachymeter

The tachymeter became popular as early as the 1930s, when it was mainly used in aviation, motor racing and shipping. Before the digital age, it was an indispensable tool for pilots, racing drivers and captains, enabling them to calculate speeds quickly and without the need for additional equipment.

Practical everyday uses of the tachymeter

Even though smartphones and GPS now display speeds accurately, the tachymeter has not lost its appeal. A tachymeter watch is not only a stylish accessory but also a practical tool. Here are a few situations in which it proves useful:

• Running training: How fast do you run a 400-metre track or your usual route? Time yourself and read off your average speed.
• Hiking: Work out your pace on familiar hiking routes.
• Cycling: Measure your speed between two kilometre markers.
• Horse racing or other races: Calculate the speed of participants over a defined distance.

As a general rule: as soon as you know the length of the route, you can easily calculate most speeds using your tachymeter watch – without a smartphone or other external devices.

Tips for accurate measurements

The longer the measurement takes, the more accurate the result. With a measurement lasting just 7 seconds, a reading error of one second can already result in an inaccuracy of 14 per cent. With a measurement time of 30 seconds, the deviation is around 3 per cent.

On most tachymeter watches, the distance travelled can be measured in short intervals ranging from 15 to 75 seconds. Therefore, for precise results, you should choose distances where the measurement takes at least 15 to 20 seconds.

Tachymeter vs. other scales

In addition to the tachymeter, there are other scales found on chronographs:

• Telemeter: Measures distances using sound (e.g. the distance to a thunderstorm)
• Pulsometer: Determines heart rate by counting a specific number of heartbeats
• Decimal scale: Displays decimal minutes for technical applications
• Slide rule bezel: Logarithmic graduations for more complex calculations (not to be confused with the tachymeter)

The tachymeter is the most commonly used scale, as speed measurement is relevant to many applications.

A design element with a function

Today, the tachymeter is rarely used for actual speed measurement. Nevertheless, it can be found on many chronographs, and for good reason. The striking scale lends a watch a sporty, dynamic character. It evokes the golden age of motorsport and combines function with history. For many watch enthusiasts, the tachymeter is therefore not just a technical detail, but a piece of watchmaking tradition on the wrist.

Tachymeter watches from MIYEN MUNICH

Do you live life at your own pace? At MIYEN MUNICH, we combine timeless design with well-thought-out functionality. Our Voyager collection is equipped with a stopwatch and tachymeter function, so it not only tells you the time but also measures your speed. In addition, the Voyager features a stopwatch function and a 24-hour display, which make measuring time easier.

These features make the Voyager tachymeter watch from MIYEN MUNICH a reliable companion, whether in everyday life, on the racetrack or whilst hiking. With the ability to calculate your own speed without needing a smartphone or other external devices, this watch combines high quality with durability.

Discover our ‘Voyager’ collection now, featuring a useful tachymeter function, and experience how form and function come together perfectly.