Square

A square case has equal width and height. It carries a strong 1920s and 1930s art deco association because that is when the format peaked. The corners are the design's personality and its main practical problem. A 34 millimeter square measures about 48 millimeters across its diagonal, so it covers noticeably more wrist than a 34 millimeter round watch. On a narrow or steeply curved arm the corners can dig in.

Inside, those corners are usable space. Designers put subdials, date windows and applied numerals where a round dial has nothing, so square watches often look busier at the same size. Sealing a corner is harder than sealing a circle, which is one reason square cases often carry only 30 meter, 3 ATM, water resistance. Read that figure literally: it means splashes and rain, not swimming.

Servicing costs more. Crystals are shaped to the case rather than pressed from stock circles. Many square watches also use fixed or integrated straps, so you cannot simply drop in a standard spring bar band. Against that, the shape is distinctive without shouting, and on a flat wrist it sits beautifully, with all four corners meeting skin evenly.

Measure the flat top of your wrist rather than its circumference, then hold that figure against the case diagonal. A 34 millimeter square runs about 48 millimeters corner to corner, so a 45 millimeter flat top leaves the corners hanging over the edge. A round case of the same stated size covers roughly a fifth less skin and traps less warmth under the caseback. Corners also take the knocks. Door frames and desk edges hit them first, so the finishing on the four corners dulls years ahead of the flat sides.