Case thickness refers to the measurement of the depth or height of a watch case, typically expressed in millimeters. It is a crucial aspect of watch design and aesthetics, influencing both the appearance and comfort of the timepiece on the wrist. A thinner case often conveys elegance and sophistication, making it suitable for dress watches, while a thicker case can suggest robustness and durability, often associated with sports or dive watches.

The thickness of a watch case can affect its weight and how it fits under clothing, such as shirt cuffs. It also plays a role in the watch's water resistance and the type of movement it houses. Mechanical movements, especially those with complications, may require a thicker case to accommodate the intricate components, whereas quartz movements can allow for slimmer designs.

Manufacturers strive to balance case thickness with functionality and style, often using advanced materials and engineering techniques to minimize bulk without compromising performance. Collectors and enthusiasts may consider case thickness when evaluating a watch's design, comfort, and suitability for various occasions. Ultimately, case thickness is a key factor in the overall wearability and visual appeal of a watch.