Undershirt vs T-Shirt (What is the Difference)

Mand modeling shirt
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Before the undershirt evolved into something specialized and totally different, the terms undershirt and t-shirt were once interchangeable and pretty much were considered the same thing. 

After all, can’t you throw any old shirt underneath your dress shirt and call it a day? 

But, these days, that answer is no, as the undershirt has taken on an entirely new purpose and meaning than what it used to have. 

For some, it still may be seen as a fashion accessory, but for many of us, it’s a basic necessity that keeps us from getting, well, gross. 

So, what is the difference between an undershirt and a t-shirt then, and why have we gotten so particular? 

In this article, we take a look at the differences between the undershirt and the t-shirt and how we’ve gotten to this point of differentiation.   

What are undershirts for?

Okay, let’s start with the basics – what is an undershirt, and what is it used for? An undershirt used to primarily be a sleeveless tee, made of a thin, cotton material. 

The word undershirt itself is mostly used in Canada and the US, whereas in the commonwealth countries, it’s often referred to as a vest. 

While usually meant to be worn underneath your everyday clothing, it is not uncommon for undershirts to be worn entirely on their own in swelteringly hot climates like India or as short sleeveless tops for athletics, which primarily applies to women. 

If you do a quick search for men’s undershirts, you will notice that you will see as many short-sleeved tee styles as you do sleeveless styles, as many prefer this type of look over the classic “wife-beater.” These short-sleeved tee styles come in both crewneck and V-neck styles. 

So, what is an undershirt actually for? 

The main purpose of an undershirt is to absorb your sweat, so it would be difficult to argue that the Polo you purchased from Ralph Lauren, which is also classified as a t-shirt, serves that same purpose. 

In fact, an undershirt could be worn underneath this type of t-shirt, as it is meant to provide a protective layer between your body and the clothing you wish to show off to the world – namely, your more expensive clothing. 

While undershirts mostly exist to keep you cool and absorb sweat, others serve a different purpose. 

Some are specifically meant to provide insulation, while others are worn to compress and “slim down” your figure. However, this is not what undershirts are most commonly used for. 

What Is a T-Shirt?

The t-shirt first became popular in the 1960s, when the printed t-shirt became known as a way to express yourself with quotes, slogans, photos, advertisements, protests, and souvenirs.

Now, the t-shirt is probably the most worn clothing garment in existence, with everyone from babies to seniors regularly sporting a t-shirt of some kind. 

While t-shirts are generally classified as short-sleeved shirts, they have branched into many other subcategories depending on their collar, neck shape, use of buttons, and more. 

A t-shirt is meant to be seen and worn on its own unless it is used as a layering piece underneath a sweatshirt, sweater, or cardigan for warmth. 

This is one of the ways in which a t-shirt is somewhat similar to an undershirt, although you wouldn’t usually strip down to just your undershirt unless you were swelteringly hot.

When Is the Best Time to Wear an Undershirt?

man in v-neck shirt

If you live in a warmer climate, then you’re probably rocking the undershirt all year round, but if you don’t, the best time to wear an undershirt is in the summer months (or if you’re lucky enough to escape to a tropical island). 

While you might enjoy the undershirt so you can wear your short-sleeved shirt with a couple of buttons undone, so you’re not showing too much chest hair, most people either consider it a sweat rag or as underwear for the upper body. 

If you’re looking for an option to keep you insulated in cold, snowy weather, then the classic long-sleeved Long Johns are technically considered undershirts as well. 

Also known as a “thermal underwear top,” Long Johns serve an opposite purpose to the traditional sweat rag undershirt. 

These types of undershirts are generally quite cheap and are made of a combination of cotton and polyester (check out the ultra-affordable Indera Men’s Traditional Long Johns Thermal Underwear Top on Amazon here!). 

What Is the Difference Between a T-Shirt and an Undershirt?

Okay, so now that we’ve established what an undershirt and a t-shirt are, what are some of their key differences? 

First and foremost, it’s important to remember that an undershirt is considered underwear, while a t-shirt is considered outerwear. 

So, while you technically can wear an undershirt as a t-shirt and a t-shirt as an undershirt, neither are designed to do the job of the other.

Let’s take a look at more key differences between a t-shirt and an undershirt:

  • T-shirts are generally thicker than undershirts, with undershirts being designed to keep you cool
  • T-shirts are most often worn alone, while undershirts are always worn underneath an outer garment
  • T-shirts should be washed after every wear since these outer layers come in direct contact with sweat, odors, and body oils, while undershirts can be washed a little more sparingly since they’re hidden underneath your clothes
  • T-shirts can be worn untucked, while undershirts should stay tucked in
  • T-shirt sleeves are usually longer than undershirt sleeves
  • T-shirts have a shallower V-neck than undershirts
  • T-shirts are looser fitting, while undershirts are usually more fitted so as not to add extra bulk underneath clothes

A Brief History of T-shirts and undershirts

So, how did we end up with the modern-day undershirt, and who was the genius who thought it up in the first place? 

Before the 20th-century, undergarments were not to be seen in public under any circumstances – therefore, they were never included in any photographs, illustrations, or paintings illustrating the undershirt. 

Showing anything but the cuffs and collars of your shirt up until the end of the 19th century was basically considered taboo, and even today’s modern-day dress shirt would have been considered an undergarment in comparison. 

The poor working class would begin to wear a tunic made of wool or flannel underneath their clothing to keep warm, which would later become the sleeveless undershirt that we know today. 

However, if someone of a higher class were to need extra insulation, he would simply add more layers on top of his existing clothing, never even considering an undergarment. 

During World War II, the t-shirt became popular, as soldiers began to wear them underneath their uniforms. 

This was ideal so they could take off their uniforms and protect them from dirt or simply as a way to keep cool, choosing to wear just the undershirt on its own. 

This was after undershirt sales dropped by a whopping 75% when actor Clark Gable revealed in the film It Happened One Night that he did not wear an undershirt. 

However, by the ’50s, simple white t-shirts that had been previously worn as undershirts would be worn by such major stars as Marlon Brando and James Dean and have taken off ever since.

Should I Wear a T-Shirt as an Undershirt?

In most cases, undershirts and t-shirts are not interchangeable, so you should avoid wearing a t-shirt as an undershirt – but of course, it is entirely up to you if you wish to wear underwear as a t-shirt! 

T-shirts can generally not be worn as undershirts because t-shirts are likely to be too long and/or too wide to be worn as undershirts and will therefore bunch up underneath your shirt. 

This will lead to your pants not fitting well and show visible bunching lines through your outer shirt. 

An undershirt should be just the right length and should fit close to your body. Many undershirts are advertised with the ability to “stay tucked” and to be virtually undetectable underneath your dress shirt.

Can I Wear an Undershirt Underneath My T-Shirt?

man in v-neck undershirt

Whether or not you wear an undershirt underneath your t-shirt completely comes down to preference. 

Having said that, there are a ton of reasons why you should wear an undershirt underneath your t-shirt, including if you’re looking to protect your t-shirt from sweat and deodorant stains

As we’ve said, t-shirts and undershirts are not interchangeable, with t-shirts meant to be worn on the outside rather than as an undergarment. 

So, this not only applies to t-shirts, but dress shirts, and any other type of shirt you can think of. 

Let’s take a look at some more reasons why you may want to wear an undershirt underneath your t-shirt.

  • An undershirt will extend the life of your t-shirts, as they will need less laundering
  • Undershirts will stay tucked into your pants or shorts, unlike most t-shirts, giving your t-shirt a more-pulled together look
  • A soft undershirt will protect you from t-shirts that may be made out of stiff or rough fabric
  • An undershirt will make a light-colored t-shirt less transparent
  • An undershirt can help regulate your body temperature, making the idea of wearing a cooling, short-sleeved t-shirt more effective

Undershirt vs T-Shirt Material

When it comes to the material of undershirts vs. t-shirts, undershirts are generally meant to be softer than t-shirts and made of soft, breathable fabric. 

Cotton is the most common type of fabric used to make t-shirts, with some of the most popular kinds being organic cotton, combed cotton, slub cotton, and Pima/Supima cotton. 

The type of cotton used will largely depend on the price point, with Pima/Supima cotton being the highest quality cotton. 

This type of cotton contains extra-long fibers, making it soft and durable. Pima cotton becomes softer with every wash and can resist fading and stretching. 

Other materials that make high-quality t-shirts include polyester, poly-cotton blend, linen, and tri-blends (cotton, polyester, and rayon).

Undershirts are most commonly made from thin cotton or a cotton/polyester blend to best soak up sweat and keep you cool. 

However, you’ll also see plenty of options in a moisture-wicking polyester and other synthetic fabrics, as well as the increasingly popular MicroModal. 

The Bottom Line

While you wouldn’t think that the undershirt and the t-shirt would really be that different, they are worlds apart when it comes to their use, purpose, and function. 

Both are designed to function completely differently and are two different types of garments altogether – undergarments and overgarments. 

While your fashion choices will always be up to your personal preference (as in, we can’t tell you what to do), we don’t recommend wearing a t-shirt as an undershirt, and vice-versa. 

Looking for more down-to-the-basics fashion advice? Visit our blog to find out everything you’ve ever wanted to know about men’s fashion.

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