Caliber
The specific model designation of a watch movement — its 'engine' model number.
What is a Caliber?
Caliber (sometimes spelled "calibre") is the designation given to a specific movement design. Just as a car engine has a model name, a watch movement has a caliber number or name — for example, the ETA 2824-2, the Rolex 3135, or the Omega 321. The term originally referred to the physical size of a movement (from the French word for gauge or mold) but has come to mean the movement model as a whole.
Why It Matters for Servicing
Knowing the caliber is essential for a watchmaker. Different calibers require different:
- Specific spare parts (mainsprings, jewels, stems, crowns)
- Lubricants at specific locations
- Service procedures and tolerances
- Timing specifications (beat rate, amplitude targets)
When we reference your caliber in a service update, we are confirming we have identified your specific movement and are working to its documented specifications.
In-House vs. Ebauche
Some brands manufacture their own movements entirely — these are called in-house calibers and are a mark of prestige (Rolex, Patek Philippe, A. Lange & Söhne). Others use movements produced by specialist movement manufacturers like ETA or Sellita — these are sometimes called ebauche movements. Both can be excellent; the distinction matters mainly for parts sourcing and servicing documentation.