Cotton describes the fiber, not the temperature at which a shirt will feel comfortable. A dense brushed button-down and a light, loosely fitted one can behave very differently on a warm commute. To choose between them, examine how much fabric sits against you, how the sleeves work, and whether the shirt fits the way you intend to wear it.
Start with the actual day. A shirt for an air-conditioned office after a short walk has different demands from one worn outdoors for hours. If you normally roll the sleeves, test that arrangement in the fitting room. Narrow cuffs and tight forearms can turn a supposedly breezy shirt into a bulky band around the elbow.
Give the fabric room to move
Button the shirt and reach forward as though holding a steering wheel or carrying a bag. The back should allow the movement you need without the front fastening pulling sharply. A little looseness can create space between cloth and skin; an oversized label does not guarantee that the armhole or sleeve is generous.
Inspect the surface near a light source. A very open fabric may provide the lightness you want but reveal an underlayer. If that means adding a camisole or undershirt, consider the complete combination before judging how cool the shirt will be. A darker print can disguise some visual contrast, though it does not change the garment's physical coverage.
Collar construction also changes everyday use. A firm collar may hold its shape under a jacket, while a soft one may fold more comfortably into a tote when the shirt comes off. Button the neck if you ever plan to wear it that way, and leave it open at the usual point to see how the fronts fall.
Choose a workable hem
A long curved tail can stay tucked but feel awkward worn loose with shorts. A shorter, straighter hem may work untucked yet escape from a waistband whenever you reach upward. Try the intended arrangement rather than judging length only with your arms at your sides.
Finally, read the care label before being persuaded by the sale price. If the finish you want requires regular ironing that you will not do, a slightly more textured shirt may fit your routine better. Buy the version whose worn appearance you like, not only the freshly pressed version shown in the listing.
