Why Are Undershirts so Long and Which Size Is FOR YOU

The undershirts are different sizes compared to the usual T-shirts. They are more elastic, tighter-fitting, and longer. Let me tell you why undershirts are so long and which is the correct length for you.

The undershirts are so long that they can be tucked into trousers and do not come out when worn. A long enough undershirt shall reach the middle of the buttocks. And shall be tucked into the trousers, under the shirt, so it’s not visible.

I prefer to wear an undershirt for several reasons. It gives me some support, keeps me warm and cool, and absorbs a lot of sweat so that it doesn’t transfer to my clothes. But it cannot be easy to choose the right size if you don’t know what lengths are important in an undershirt.

It’s embarrassing if sweat stains appear on your shirt. Read how to prevent sweat stains and how to remove yellow sweat stains by clicking on this link.

Why are undershirts so long and how long should they be?

The undershirts are long because they need to be tucked into the trousers and must not be untucked. The length of the undershirt must reach up to the middle of the buttocks because it is just long enough to keep it out of the trousers. And it’s not too long so it doesn’t distract you when wearing it.

As you may have noticed, the dimensions of the undershirt are slightly different from the dimensions of the shirt and the T-shirt. Undershirt should be more thingth rather than loose. That is the reason why more undershirts are tighter-fitting and longer. Therefore, when choosing undershirts, we cannot consider the exact sizes for a T-shirt. But we must try on the undershirt or select the size based on the measurements.

How long should my undershirt be?

The undershirt should reach the middle of the buttocks so that it can be tucked into the trousers and stay tucked in for the whole day. The easiest way to find out if the length suits you is to try on the T-shirt in the shop. If you order your undershirt online, you must take measurements.

I’ve already written about how to choose an undershirt that won’t be too tight in a previous article so that you can read the detailed measuring process here. Now I’ll show you how to measure the length of your undershirt.

To measure the appropriate length of your undershirt, you will need to measure the length of the front of your upper body from the start of your neck to your hips. The most accurate results will be obtained if you measure yourself without the shirt and using a tailor’s tape measure. If you do not have a tailor’s tape measure, you can use a longer piece of string or a shoelace to read the length and then measure it with the tape measure.

How to measure length of an undershirt
How to measure the length of an undershirt.

The measuring process is… Place the start of the tape measure or string at the highest part of the shoulder near the neck (see point 1 in the picture above). Then place the point of the tape measure vertically to the hip and measure to the hip bone, which you feel with your fingers (see point 2 in the picture above). The tape measure or string should connect the two points straight and be just the right tension.

Size chart for undershirt
Size chart for an undershirt.

To get the undershirt size, you need to order and enter your details in the table recommended by the seller. Although we have only measured to the hip, the undershirt will be longer and reach halfway down our buttocks.

Are undershirts supposed to be a size smaller?

The undershirt doesn’t need to be one size smaller because undershirts have different measurements than normal T-shirts. Undershirts are more tight-fitting and elasticated to fit your body well. To determine the size of the undershirt, measure your body measurements and order the undershirt based on the measurements provided by the retailer.

You will sometimes need to wear a larger undershirt rather than a smaller one, as some undershirts are very tight and elastic. If possible, try on the undershirt before you buy it, or order just one piece to start with and see how the size fits you.

Should you tuck in the undershirt?

The undershirt must always be tucked into the trousers and must not be visible at any time. The purpose of an undershirt is to keep you comfortable and to protect your clothes from sweat. On the outside, it should look like you are wearing nothing underneath your clothes.

The undershirt must be completely invisible under the clothes. The sleeves and collar must not be visible under the shirt, and the undershirt must not be visible under or above the shirt.

Undershirt should not be visible
The undershirt should not be visible.

You can read why it’s not OK for the undershirt to be visible in this post. The choice of color is also important to ensure that the undershirt is not visible. This special post can find whether it should be white, grey, or black.


My name is Gregor and I'm a sports and fashion enthusiast. Like you, I want my clothes to be good quality and comfortable. I hope my articles will help you choose the right underwear for you.

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