Glossary/Beat Error
Beat Error
Beat error is the amount of time by which the duration of swing differs from one side to the other in the oscillation of a balance wheel or pendulum.
Its value is calculated by subtracting the duration of the second vibration from the duration of the first vibration. A positive value indicates that the first vibration was longer than the second. A negative value indicates that the first vibration was shorter. Knowing whether the value of the beat error is positive or negative is not very useful with watches, but can be very useful when regulating clocks.
Beat error is generally expressed in milliseconds.