Caliber is a term that is used to distinguish different types of movements made by the same manufacturer. This term initially was used only to refer to the size of a movement, but now it designates a specific model.

Each of watch manufacturers have their own identification system to number their calibers. For the caliber indication letters and numerals are used. In most cases, watch caliber corresponds a size of the internal mechanism. Some manufactorers simply give to their mechanisms the character set for the model name. Labeling should also contain information about the number of jewels in caliber.

Many companies use ready-made watch mechanisms in the production.

At the same time, haute horlogerie maisons that are producing works of fine watchmaking, create their own calibres. It is a very complex and expensive process. As a rule, for the prototype and a mechanism development global brands invite star watchmakers - world best masters, or place their orders with watchmaking laboratories, where mechanisms are created by no less eminent and talented watchmakers.