LoupeLabBeat Rate & Frequency Converter
Convert between Hz, vph, and bph for mechanical and quartz watch movements. Enter a value in any field and the others update automatically.
vph = Hz × 7,200 • Hz = vph ÷ 7,200 • bph = vph (same unit)
Common Beat Rates
| Hz | vph / bph | Category |
|---|---|---|
| 2.5 | 18,000 | Vintage movements |
| 3 | 21,600 | Common automatic |
| 4 | 28,800 | Modern standard |
| 5 | 36,000 | Hi-beat |
| 8 | 57,600 | Ultra hi-beat |
| 32,768 | -- | Quartz crystal |
Click any row to load its values into the converter.
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Oscillations vs. Vibrations
A balance wheel swings back and forth. Each full back-and-forth cycle is one oscillation (measured in Hz). Each swing in one direction is one vibration (or beat). So 1 oscillation = 2 vibrations. That's why vph = Hz × 7,200 (Hz × 3,600 seconds × 2 vibrations).
Why Frequency Matters
Higher Frequency = Better Accuracy
A faster-beating movement divides time into smaller increments, making it less sensitive to positional errors and external shocks. At 4 Hz (28,800 vph), each beat represents 1/8 of a second, while at 3 Hz (21,600 vph) each beat is 1/6 of a second. The finer division means any single disrupted beat causes less cumulative error.
The Tradeoff: Wear & Service Life
More beats per second means more friction, more wear on the escapement, and faster depletion of the mainspring's energy. Hi-beat movements (5 Hz and above) typically have shorter power reserves and may need more frequent servicing. Modern lubricants and materials like silicon escapements have narrowed this gap, but the tradeoff still exists.
Smoother Seconds Hand Sweep
Higher frequency creates a smoother visual sweep of the seconds hand. At 4 Hz, the hand makes 8 tiny steps per second, which appears nearly continuous. At 3 Hz, the 6 steps per second are more perceptible. Hi-beat movements at 5 Hz (10 steps/sec) are almost indistinguishable from a true glide to the naked eye.
Why Quartz Is So Accurate
A quartz crystal vibrates at 32,768 Hz, roughly 8,000 times faster than a 4 Hz mechanical movement. This extreme frequency means each individual oscillation error is vanishingly small. A typical quartz watch loses or gains less than 1 second per day (roughly ±15 seconds per month), compared to ±5 seconds per day for a well-regulated mechanical. The tradeoff is purely aesthetic: no sweeping seconds hand, just a tick-tick stepping motion.
Note: Beat rate alone doesn't determine accuracy. Regulation quality, escapement design, mainspring torque curve, and temperature compensation all play significant roles. A well-regulated 3 Hz movement can outperform a poorly regulated 4 Hz movement in daily timekeeping.