Frequency is how fast a mechanical watch movement ticks. It is given in vibrations or beats per hour (vph or bph), or in hertz. It matters because it shapes how a watch behaves. A higher frequency helps a watch recover faster from knocks, but its parts wear out faster and it uses up energy quickly.
What is the difference between vph and hertz?
The two units count different things. Hertz counts complete cycles each second. Vph is the older unit, and it counts half cycles each hour. One complete cycle is an oscillation: the balance wheel swings away from where it started and comes back. A vibration, also called a beat, is half of that, so every oscillation holds two beats. To turn hertz into vph, multiply by 7,200. A movement at 2.5 Hz therefore runs at 18,000 vph, and one at 5 Hz runs at 36,000 vph.
Is a higher frequency better?
Not simply. A faster beat helps a watch recover more quickly after a knock. The cost is wear. Parts wear out faster, and high-frequency movements use up energy quickly, so they need servicing more often. Running fast also asks more of the movement itself. A 36,000 vph movement needs a stronger balance spring and a stronger mainspring to keep the balance swinging at that pace.
What frequencies do watches run at?
Older pocket watches usually run at a lower 18,000 vph, or 2.5 Hz. Wristwatches styled after them often do the same. Higher up, Seiko built high-beat movements at 36,000 vph in its Hi-Beat range. Some recent movements go far beyond the usual rates. Breguet’s Calibre 574DR runs at 72,000 vph, which works out at 10 Hz.
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