Round and rectangular watches can both work with tailoring. Compare the outline, the space it occupies on your wrist and the way it meets your shirt cuff. A familiar diameter does not translate directly into a rectangular case size, and a shape label alone does not establish how formal a watch will look.
Compare dimensions in the same direction
NOMOS lists the round Tangente reference 139 with a 35.0 mm diameter and 45.0 mm lug-to-lug length. Jaeger-LeCoultre lists the rectangular Reverso Classic Monoface Small Seconds Q3868520 at 40.1 × 24.4 mm, explicitly identifying the first dimension as lug-to-lug.
In that comparison, 45.0 mm and 40.1 mm describe length including the lugs; 35.0 mm and 24.4 mm describe width differently, through a round diameter and a rectangular width. These are published specifications for the stated genuine references, not measurements of samples tested here or a prediction of equal wearing comfort.
Look at the complete outline
A rectangular case can occupy relatively little space across the wrist while extending farther along it. Look at both directions, including where the strap begins to bend. Our lug-to-lug fitting guide covers that reach; the side view also helps you see how the case rests.
Then compare the visible dial opening, the metal surrounding it and the strap or bracelet. A broad polished border and a bright bracelet create a different impression from a narrow border and a plain strap. Avoid attributing that entire difference to round versus rectangular geometry.
Try each shape with the same clothes
Use the shirt and jacket you expect to wear most often. Look in a mirror with your arms resting naturally, then raise the wrist as you would to read the time. Compare how much of the case appears below the cuff and whether you enjoy that amount of emphasis.
If you take reference photographs, keep the viewing distance and wrist angle similar. Include an outfit view as well as a close-up. You might prefer a rectangular outline as a distinct detail, or a round case as a quieter continuation of your usual watch; those are personal visual choices, not fixed dress-code rules.
Finish with the ordinary wearing checks
Button the cuff, bend your elbow and sit at a desk. A narrow case can still catch on fabric or feel awkward, so use our watch and shirt cuff checklist before deciding that one shape solves the fit.
Finally, read the time at your normal distance and check the closure. Keep the shape that combines the appearance you want with comfortable use. Browse more clothing and watch guides in Watches & Wear.