Regulation
The process of adjusting a watch's rate so it runs as close to accurate time as possible.
What is Regulation?
Regulation is the process of adjusting how fast or slow a mechanical watch runs. Because no mechanical movement is perfect, every watch needs to be regulated — either at the factory during production, or by a watchmaker after a service.
How It Works
The rate of a mechanical watch is controlled by the effective oscillating length of the hairspring. Most movements have a regulator — a small lever or index that can slide along the hairspring, effectively shortening or lengthening the active coil length:
- Shortening the active length → the balance wheel oscillates faster → the watch gains time
- Lengthening the active length → the balance wheel oscillates slower → the watch loses time
Higher-grade movements use timing screws on the balance wheel rim instead of a regulator lever, allowing more precise adjustment by changing the rotational inertia of the wheel.
Positional Regulation
A well-regulated watch should keep accurate time in multiple positions — dial up, dial down, crown up, crown down, and so on. Gravity affects the balance wheel differently depending on orientation, so high-grade watches are regulated in five or six positions. This is why a service report often mentions that your watch was regulated across positions and tested on a timing machine.