A caliber can be described as the type of movement used in a watch. It is expensive and impractical to design a unique movement for each watch model, so most manufacturers often use the same movement in different watch models, sometimes with significantly different designs. The term "caliber" is due to the fact that initially the type of movement was designated by a number (in inch lines) corresponding to its largest size; however, today unique names or alphanumeric indices that are not directly related to sizes are widely used.
Knowing the name of the caliber on which the watch you are interested in is built, you can, if desired, find more detailed information about the mechanism and determine how its characteristics meet your requirements.
The nominal size of a watch case in diameter (for round cases) or width (for other options, see "Case Shape"). In the most miniature modern models, this size is
21 – 25 mm or even
less, among the largest there are cases of
46 – 50 mm and even
larger.
Larger watches are more convenient in the sense that the dial readings are better visible on them, and it is easier to provide various additional functions in the design. On the other hand, small watches look neater and create less discomfort directly when worn. In addition, female models (see "Gender") are traditionally made more miniature than male ones. So the choice for this indicator depends mainly on the intended specifics of the application: for example, large cases are best suited for outdoor activities and tourism, about
41 – 45 mm in size, for household wear (regardless of gender) — about
31 – 35 mm, and as an accessory to an evening dress, a small watch of
30 mm or less would be more appropriate.
Also note that the size of a compatible strap/bracelet is associated with this indicator — see "Strap Width" for details.
The thickness of the watch case. A fairly obvious parameter; we only note that nowadays it is customary to attribute watches with a thickness of less than 7 mm to
ultra-thin models. This design has both aesthetic and quite practical meaning — a thin watch will be useful for those who wear narrow sleeves with tight-fitting cuffs.
