The diameter of the dial or face in millimetres is referred to as the watch size. The size of a watch that is best for a woman will vary depending on personal preference and the size of her wrist. However, as a general rule of thumb, watches with a case diameter of 34mm to 40mm are considered to be a good size for most women. We have different sizes of watches for women. Ultimately, the best size for a women's watch will depend on the choice of look she is trying to achieve.