Firstly, let’s define the difference between the two. Often confused with each other, the undershirt and t-shirt are, in fact, two completely separate items of clothing with different purposes in your wardrobe.

The Undershirt  

The UNDERSHIRT is a base layer shirt worn next to the skin. Its function is to minimize the everyday sweat and underarm deodorant stains from soiling your dress or t-shirts, helping to minimize the number of times they need to be laundered and therefore extend their life. 

The undershirt is actually not a shirt, it is underwear. Just as you wouldn’t go outside in your jockey shorts, you should not be wearing an undershirt as your outermost item of clothing. 

The undershirt is made to be worn under another shirt, so it is thinner and lighter than a t-shirt. It is available in a limited number of muted colors such as white, grey, black and tan so as not to show through your outer shirt. 

Undershirts are usually worn under a collared work shirt. They also give you an extra layer of coverage under a lighter fabric dress shirt, thus avoiding that embarrassing see-through look. 

Undershirts are slightly stretchy with a snug fit and are not made to be worn on their own. 

The T-Shirt

The T-SHIRT, however, is worn on the outside exactly like a normal shirt.

black tee with undershirt – Bearded man with sunglasses and hat wearing a black tee-
shirt with an undershirt.

It is thicker than an undershirt and comes in a variety of colors, absorbing sweat like any other shirt. 

Undershirts and t-shirts are not interchangeable, however, so it is not advisable to wear a t-shirt as if it is an undershirt, as it will bunch up and show unattractive visible lines through your outer shirt. Not a cool look.

T-Shirt vs Undershirt?

Looking for more information on the differences between undershirts & t-shirts? Check out our T-Shirt vs Undershirt article covering the top 9 ways they are different.

Should you wear an undershirt under your t-shirt?

Now that we’ve defined the difference, should you wear an undershirt under your t-shirt – or even golf or polo shirt? 

The answer is both YES and NO. 

Can you wear a t-shirt without an undershirt? Sure, many do -- and it really boils down to personal preference & comfort.

Should you wear an undershirt under your t-shirt? Absolutely, especially if you want to add extra life to your outer shirts. 

Here’s why it’s important to wear an undershirt even under your t-shirt:

Protection from Body Sweat and Odors

Wearing an undershirt under your t-shirt prevents the armpit areas from becoming stained and stiff from sweat and deodorant staining. 

It will extend the life of your t-shirts as they will need less laundering. 

Stays Tucked-in Better

The typical T-shirt cut is very short and won't stay tucked into your pants all day. 

Undershirts are cut longer than your average t-shirt, so they stay tucked into pants or shorts and provide a more pulled-together look. 

Protection from Stiff or Rough Fabric

An undershirt is comfortable and soft and can protect your skin from an itchy or rough fabric. 

If your current undershirt isn't soft, you are wearing the wrong type. 

Makes White T-shirts Less Transparent

Light-colored t-shirts can be transparent. With a little sweat or water, they can become embarrassingly see-through. 

Man wearing undershirt under teeshirt – Man standing in narrow street wearing a white t-shirt with an undershirt underneath

Wearing a good-fitting undershirt underneath a light-colored t-shirt ensures a solid visual barrier which will absorb the sweat that may have made it transparent. 

Looks Better

Undershirts help smooth out your body contours. 

Nipples and chest hair peeking through your shirt are a fashion faux pas, so a well-fitting undershirt that contains compression will help reduce the appearance of any unsightly characteristics of your physique. 

Helps Regulate Body Temperature

Not only can a good quality undershirt feel good against the skin, but it can also help regulate body temperature. 

Today’s undershirts will either keep you warm in the winter or cool in the summer. A thicker undershirt helps you stay warm in the winter and a breathable, absorbent shirt to wick the sweat away helps your body temperature remain stable in the summer. 

If you are wearing your favorite t-shirt on a warm day, be sure to add an undershirt with a cooling fabric underneath to keep you comfortable. 

What fabric should you choose for an undershirt? 

Here are our suggestions -

Fabric options:

  • Undershirt fabric should be thin, stretchy and soft. 
  • Choose high-quality 100% cotton such as Egyptian or Supima cotton.
  • Another option is a stretchy combination of cotton and synthetic fibers (such as rayon) that retains its smooth shape.
  • Modern technical fabrics, such as TENCEL are buttery-soft with sweatproof or moisture-wicking properties. 

What undershirts styles are there? 

Undershirt style options include:

  • Tank top – sleeveless; doesn’t absorb sweat making its main function to just hide nipples and smooth down chest hair.
  • V-neck – wear this with V-neck tees so you can be stylish without your undershirt peeking through.
  • Crew neck – the most common style to wear with a typical standard tee.
  • Long sleeve (crew neck usually) – great for warmth when sweat isn’t your main concern. 
  • Compression – best for smoothing the appearance of lumps and bumps.

What should I know about undershirt fit?

Your undershirt should be close-fitting with small armholes to allow it to absorb sweat under your arms and prevent bunched fabric underneath your t-shirt. 

It should feel snug but comfortable, without restricting your movement - and should stay tucked into your pants. 

Also, make sure the neck opening is bigger than your t-shirt collar to prevent the collar from bunching around your neck or peeking out from under your t-shirt. 

A carefully crafted, quality undershirt smooths out the torso, so your shirt lies flat across your body.

What should I wear under A V-Neck T-Shirt?

As you should never let your undershirt show, always opt for a style with flat seams. 

Remember that cheaply made undershirts can be seen underneath a man’s dress shirt even if it is buttoned all the way. When you are wearing a shirt with a lower neckline than a typical crew neck, such as a V-neck shirt, wear a thin, close-fitting V-neck undershirt so that it isn’t visible underneath. 

We have two styles to choose from:

  • Regular V-neck undershirt - these are best for wearing under a V-neck t-shirt or under a shirt with the top button not fastened.
  • Deep V-neck undershirt - this style works best under a buttoned shirt with the top two buttons left unfastened.

The bottom line is – the undershirt should be a staple in every man’s wardrobe and is made to be worn under a t-shirt. 

It’s practical, comfortable and preserves the life of both dress shirts and t-shirts alike. 

Try one on, wear it for a day or two and you’ll understand.

Check out our Most Popular Undershirts for a great selection.