Beats per hour (bph) is the unit used to measure the oscillation frequency of a mechanical watch movement's balance wheel — specifically the number of half-oscillations, or beats, the balance wheel completes in one hour. Each beat corresponds to one audible tick and one incremental advance of the escapement. A movement running at 28,800 bph completes 28,800 half-oscillations per hour, or 8 per second. This is one of the most commonly cited movement specifications because it directly affects the visual behaviour of the seconds hand and the movement's theoretical resistance to positional timekeeping errors.
In replica watches, the most common beat rates are 21,600 bph and 28,800 bph. Miyota movements typically run at 21,600 bph, producing a seconds hand that advances in clearly visible steps — approximately 6 ticks per second. Higher-grade clone movements running at 28,800 bph produce smoother, faster seconds hand motion that more closely resembles the fluid sweep associated with high-end genuine movements. The beat rate of a movement does not directly determine its accuracy — a well-regulated 21,600 bph movement can keep better time than a poorly regulated 28,800 bph movement — but higher beat rates are generally associated with premium calibres and more refined timekeeping characteristics.
In Practice
- The seconds hand motion of a replica watch is directly determined by its beat rate. At 21,600 bph, the seconds hand advances 6 times per second in clearly distinct steps. At 28,800 bph, it advances 8 times per second, producing a smoother visual sweep. Buyers who prefer a more fluid seconds hand motion should look for replica references specified with 28,800 bph movements.
- Common beat rates in replica watch movements: Miyota 8215 and most Mingzhu calibres run at 21,600 bph. Higher-grade clone movements inspired by ETA 2824 and similar Swiss calibres typically run at 28,800 bph. Seiko NH35-based movements run at 21,600 bph. The beat rate is usually listed in movement specifications alongside diameter, thickness, and power reserve.
- Beat rate affects power reserve indirectly — higher frequency movements generally consume mainspring energy faster, which can result in slightly shorter power reserve compared to lower frequency calibres of similar size. This tradeoff is rarely significant in everyday wear but becomes relevant when comparing movement specifications across calibres.
- The audible tick rate of a mechanical watch corresponds directly to its bph. A watch running at 21,600 bph produces 6 audible ticks per second; one at 28,800 bph produces 8. This is a practical way to estimate a movement's beat rate without access to specification documents — count the ticks for one second and multiply by 3,600.
- Beat rate should not be confused with accuracy. A movement's beats per hour determines its oscillation frequency; its accuracy is determined by how consistently that frequency is maintained across different positions and temperatures. Regulation — adjusting the effective hairspring length — corrects accuracy independently of beat rate.
Related Terms
Balance Wheel · Escapement · Automatic Movement · Miyota Movement · Mingzhu DG2813 V4
Read Next
For a full overview of movement types and calibre specifications used in replica watches — read: Replica Watch Movements Explained