What does the frequency of an automatic watch mean?





In watchmaking, the frequency of movement is a true marketing asset. Many brands have launched a race to increase the swing speed and performance of their watches. But what about this famous frequency?

The frequency explained

balance spring shows

The balancing spring is at the heart of the clock. When you swing, it will allow you to deliver time accurately. The frequency of movement corresponds to the number of round-trip movements of the balance per hour. An oscillation (a “ticking”) corresponds to two half waves (forward and backward).

This frequency can be expressed in hertz (Hz) or alternatively per hour (A / h).

The most common frequency for modern mechanical watch movements is 4 Hz, or 28,800 vibrations per hour. A clock that rotates at 4 Hz performs 4 oscillations per second or 8 half oscillations per second. Knowing that there are 60 seconds in a minute, this produces 480 half oscillations (or vibrations) per minute. If you multiply 480 vibrations per minute by 60 minutes of one hour, you will get the figure of 28,800 vibrations per hour. Therefore, a chronograph of a watch at 28,800 vibrations per second can time an event at 1/8 of a second.

For example :

  • Frequency of 2.5 Hertz = 18,000 vibrations per hour (A / h)
  • Frequency of 3 Hertz = 21,600 vibrations per hour (A / h)
  • Frequency of 4 Hertz = 28,800 vibrations per hour (A / h)
  • Frequency of 5 Hertz = 36,000 vibrations per hour (A / h)

The numbers obviously do not stop there and go much higher. The test with quartz watches, which mostly have a frequency of 32 MHz.

Advantages and limitations.

silicone exhaust wheel

Since the increasing accuracy of the movement coincides with a rapid increase in frequency, it can be concluded that the higher the frequency, the better the accuracy.

However, you should know that a very high frequency will consume more energy, cause a loss of autonomy of the energy reserve and more mechanical problems. In addition, this requires a smaller pendulum. Therefore, it will be more sensitive to disturbances that the movement of the watch may suffer, while a larger and heavier balance will be more capable of coping with possible shocks.

Nicolas Forni

Passionate about watchmaking, I launched Mr Watch at the end of 2015! Join me and discover new brands and follow the latest news from the world of watchmaking.