Updated October 2026
These four numbers are the complete list of beat rates this tool supports, and picking the right one for your watch matters — see what is beat rate (bph) for why. This page compares all four side by side: what era and type of movement typically uses each, and the actual math behind how they sound different.
Every beat rate implies a fixed theoretical time between ticks: 3600 seconds ÷ bph = seconds per beat. Converting to milliseconds for all four:
| Beat rate | Frequency | Interval between ticks |
|---|---|---|
| 18,000 bph | 2.5 Hz | 200 ms |
| 21,600 bph | 3 Hz | 166.7 ms |
| 28,800 bph | 4 Hz | 125 ms |
| 36,000 bph | 5 Hz | 100 ms |
These are exactly the theoretical values analyzeTicks() compares your watch's measured average interval against — see how this works for the full rate calculation.
Common in watches and pocket watches made before roughly the 1960s-70s, and in many budget or simpler movements of that era. The 200ms gap between ticks is long enough that a tick and tock are quite distinctly separated to the ear, sometimes described as a slower, more deliberate "tick... tock" rhythm.
Widely used through much of the mid-20th century, and notably still chosen deliberately by some current manufacturers (a few well-known in-house calibers run at this rate specifically) — a slower beat rate puts less wear on escapement components over time, trading a little bit of theoretical timekeeping smoothness for potentially longer intervals between services.
By far the most common rate across mechanical watches made since the 1970s onward — most ETA and Sellita movements, and the large majority of current in-house calibers, run at this rate. If you're not sure what your watch uses and it's a reasonably modern mechanical watch, 28,800 is the best first guess.
Less common, found in watches specifically marketed around their high-beat movement. The 100ms interval produces a notably smoother, more rapid-fire ticking sound and a visually smoother-sweeping seconds hand than lower beat rates. High-beat movements historically carried some chronometric prestige (finer time subdivision, in theory steadier short-term rate) but also run with more friction and wear per unit time, which can mean shorter recommended service intervals.
With practice, roughly — the difference between 18,000 and 36,000 bph is audibly obvious (roughly a 2x difference in tick frequency), but adjacent rates like 21,600 vs. 28,800 can be harder to distinguish confidently by ear alone. A documented caliber specification is always more reliable than an ear-based guess; see finding your watch's bph for where to look it up.
Are there mechanical watches that use rates outside these four? Yes, a small number of unusual or specialty movements exist outside these values, though the four listed here cover the large majority of watches in circulation.
Does a faster beat rate always mean a "better" watch? Not inherently — it's one design choice among many that affects smoothness and theoretical short-term timekeeping, traded against wear and servicing considerations; overall watch quality depends on far more than beat rate alone.
Will selecting the wrong rate still detect ticks, just report wrong numbers? Yes — onset detection is independent of bph selection; only the rate and outlier-rejection math at the final step depends on picking the right value. See what is beat rate (bph).