In watchmaking, "calibre" (or "caliber" in American English) refers to the specific model or design of a watch movement, which is the mechanism that drives the watch and powers its functions. The calibre is essentially the heart of the watch, comprising various components such as gears, springs, and escapements that work together to measure and display time. Each calibre is unique, often designed and manufactured by watchmakers to meet specific functional and aesthetic requirements.

Calibres can be mechanical, automatic, or quartz, with each type offering different advantages. Mechanical calibres are powered by a mainspring and require manual winding, while automatic calibres are self-winding, harnessing the motion of the wearer's wrist. Quartz calibres, on the other hand, are battery-powered and known for their precision and low maintenance.

The design and complexity of a calibre can significantly influence a watch's value, performance, and appeal. High-end watch brands often develop proprietary calibres, showcasing their craftsmanship and innovation. Collectors and enthusiasts frequently discuss calibres when evaluating watches, as they reflect the technical prowess and heritage of the watchmaker. Understanding the calibre is crucial for appreciating the intricacies and artistry involved in horology.