Making an untucked shirt work
The hem and body length matter more than a blanket rule about tucking.
An untucked shirt can look relaxed and complete, but not every shirt is cut with that use in mind. A long formal shirt may have tails intended to stay inside trousers. A shorter casual shirt may finish more evenly. Start by examining the garment rather than asking whether men should always tuck shirts in or leave them out.
Read the length from several angles
Look at the front, side and back. A shirt can seem short enough at the front while its rear tail hangs much lower. Notice how much of the trouser pockets and fly it covers. There is no ideal measurement for every body, but if the shirt conceals nearly all the upper trouser shape, you may prefer a shorter cut.
Try raising your arms and sitting down. A shirt that is attractive standing still may ride up too far or bunch awkwardly around the hips. Sizing down can shorten it, but may also tighten the chest and collar. A different body length is often a better answer than forcing the wrong size to perform another job.
Choose trousers that support the shape
A straight or gently tapered trouser gives an untucked shirt a clear base. Very narrow trousers beneath a wide, long shirt create more contrast; that may be intentional, but it is worth checking rather than accepting by default. The trouser rise also changes how much of the body the shirt covers visually.
A light blue Oxford shirt over olive chinos is an easy casual example. A patterned short-sleeve shirt over plain trousers can work too, especially when the shirt's hem is relatively clean and straight. Avoid adding a busy jacket if the shirt already has a strong print and loose shape.
If you wear a jacket, compare their lengths. An untucked shirt projecting far below a short blazer can look disconnected, while a casual overshirt or longer outer layer may accommodate it. Alternatively, tuck the shirt for that particular combination. You do not need to commit to one method for the garment's entire life.
Consider the setting before the silhouette. Some workplaces or occasions expect a tucked shirt regardless of how good an untucked one looks. For casual settings, choose the arrangement that stays comfortable and requires the least correcting. If you keep folding the hem under or pulling it sideways, the length is probably not working as well as you hoped.
