Knowing the differences between undershirts and t-shirts, and why it matters

Man is a homeothermic creature. In excessive heat, he wears as little as possible and in blistering wintery periods, he bundles up as much as possible. This is completely logical. Somewhere in-between these extreme weathers, he makes decisions on the degree of heat or cold he can tolerate, then takes a gamble on his choice of clothing. When it comes to undergarment choices, particularly for the upper body, it becomes confusing, or in most instances overlooked. It is common that he swaps a t-shirt for an undershirt, particularly in frosty weather when layering is the norm. Vice versa, on warm days without a cloud in the sky.

Let’s start with the first principle; undershirts are undergarments. Therefore, substituting an undershirt for a t-shirt is inappropriate, as is substituting a t-shirt for an undershirt. It is important to draw the distinction between these two types of clothing. In my view, there are three key reasons why an undershirt differs to a t-shirt. They centre around: choice of fabric, design & style, purpose & occasion. Let’s take them one at a time.


Choice of Fabric

The rule of thumb is that the choice of fabric for undershirts should be comfortable because it is the first contact with their skin. So, attributes like the weight of the fabric are a primary consideration for undershirts, as are thickness, breathability, stretch, tension, moisture wicking, and friction. T-shirts can be made with all of these in mind, but because they are not undergarments, are not primary requirements.  Can you imagine a man wearing an undershirt from heavy coarse fabric? Or from impermeable and ultrasmooth fabric, to the point where the undershirt slides around his body? Both would be equally uncomfortable. This makes fabrics from natural fibres – breathable, soft, and light, ideal for undershirts, and fabrics from synthetic or blended fibres - with coarser textures, and heavier weight, suitable for t-shirts.

Undershirts should ideally be designed with knit fabric. Due to its singular yarn structure, which is looped together, it offers far more stretchability than woven fabrics which consist of two sets of yarns that are orthogonally interlaced together, so offering little stretchability if any at all. Therefore, the fabric of a high-quality undershirt should offer a four-way stretch so it can move seamlessly with the body, stretching and adapting to it, while t-shirts can have varying degrees of stretch ability woven or knitted into its fabrics, or none.

The constant attribute between an undershirt and a t-shirt is durability. Their fabric properties should ensure longevity; able to withstand chemicals and multiple washes; resistant to tearing and piling; and keeping its shape and structure. Although, t-shirts, which are designed to withstand external elements, have the edge over undershirts when it comes to durability. Nonetheless, the fabric of the undershirt should be durable enough to function as a foundational layer for the garment.

In summary, the fabric of an undershirt should complement the fabric of a garment, never to overpower it.


Design & Style

Felt but not seen, is the true test of an undershirt. Like the webbed feet of a Bewick’s swan, the undershirt should allow you to effortlessly go about your day whilst your garments look elegant. Its low neckline, high armhole, and short sleeves are key features of its design, so that at no point do they become visible. This contrasts with a t-shirt, often with a high neckline, lower armhole, and longer sleeves, so that the t-shirt can be seen, the armhole big enough to accommodate an undershirt, and the sleeves draped at the end of the lower bicep giving fullness and coverage over the undershirt.

The openings of the neck and body are also worth noting. With undershirts, the neck opening should have a wider and deeper groove so that it rests on the lower slope of the shoulders. The t-shirt should have a smaller opening and sit higher on the shoulder slope. This consideration in design, opens the undershirt to neck styles such as V-necks and scoop necks, and for t-shirts neck styles such as close-to-the-neck crew neckline, polo collar, Henley collar, and a lot more. T-shirts due to the design of the neck opening, has a wider variety of styles than an undershirt. The body of an undershirt should converge from the chest to the hem with the intention of hugging the waist and wrapping itself around the haunches, giving full protection of the back, whilst the body of a t-shirt should diverge from the chest to the hem, giving room for an undershirt.  



Another distinction is the length. An undershirt, a well-designed undershirt, should have a longer body length than a t-shirt; this is to prevent untucking and exposure in active or passive positions. Such faux pas should not be taken lightly and goes against the grain of fashion etiquette, universally. For this reason, the Eustace Designs undershirt Torso, has a back length of four inches more than the front length, so it solves the untucking problem. It also ensures that men who have a longer upper body in proportion to their lower body, avert the same problem.

Simply, undershirts are designed to prevent embarrassment, t-shirts are designed to make a statement. 



Purpose & Occasion

When we remind ourselves of the first principles of an undershirt: that an undershirt is an undergarment, it becomes clear that it would be inappropriate for any other purpose.  

Can you imagine a man at the supermarket in his boxer briefs even though it is ‘bulge-proof’? He might wear a pair of shorts to the supermarket but never boxer briefs. Maybe it is because it would be considered unfashionable and inappropriate to do so, and maybe it is because boxer briefs are in fact undergarments. The same logic applies to an undershirt and a t-shirt. Boxer briefs are to be worn under shorts, not on top, and not as a substitute. Likewise, undershirts are to be worn under t-shirts, and not as substitutes.

The purpose of an undershirt includes being the first layer of protection to the skin from stiff or otherwise uncomfortable garments, protecting the garment from sweat that seeps to the surface, and body oils that leave marks on areas like the collar. It also prevents deodorants stains, caused by the aluminium and zirconium present in deodorants, from over time leaving a solid yellowish stain on the armpit, which damage the garment.

Simply put, the undershirt’s raison d’etre is ensuring longevity of the garment.  

For very light-coloured garments, undershirts create an opaque layer that helps conceal markings like tattoos (should you have any).

The t-shirt is not a natural undergarment and because of its design, cannot present a smooth, seamless appearance under your garment. All of these are what an undershirt does to help the garment look sophisticated, like a pair of black ribbed dress socks to a pair of black handmade Oxford shoes.

The undershirt’s versatility – foundational layer, ‘concealer’, and close fit design - make it suitable for casual, semi-formal and formal occasions.


Man in tuxedo walking down the street holding gift box

In respect of the above, undershirts should be worn under all types of shirts, from simple t-shirts and polo shirts; to dress shirts and evening shirts; and knitwear, just to name a few.


Do you wear undershirts? Let us know in the comments.


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