A thermal shirt is usually a round, or crew, necked shirt with long sleeves. Its purpose, like all thermal clothing, is to retain body heat in cold temperatures. Many thermal shirts are made of silk, nylon, spandex, polyester, fleece, wool or a cotton blend. Thermal shirts are used as base layer for cold weather dressing.

A thermal shirt may also have a stand up type collar, which increases the warmth factor. The shirts are often used for fitness and exercise and are touted to prevent overheating during strenuous activity. A thermal shirt is sometimes layered under t-shirts or sweaters or even worn alone. Often, thermal shirts are advertised to keep the wearer dry by wicking moisture from the body, so they are ideal for athletes.

Thermal shirts are often knit in a waffle-weave pattern that assists in trapping body heat. Many thermal shirts have ribbed knit cuffs to prevent cold air from entering the sleeve area. A thermal shirt is most likely to be washable. Some shirts contain anti-microbial properties to reduce odor and often have flat seams that reduce chaffing.

Once only found in basic colors and as a utilitarian type item, more design options have emerged as thermal shirts have become more popular. A thermal shirt can be purchased in nearly any price range, from $10 US Dollars (USD) to $100 USD.

Not only designed for men, thermal shirts are also popular for women. Women’s thermal shirts tend to have stylish features such as v-necks or scoop necks and a more slimming silhouette. Some thermal apparel has been manufactured from bamboo grown without pesticides and made with biodegradable dyes.

In addition to thermal shirts, many other thermal apparel items are manufactured, including thermal underwear, socks, jackets, hats, gloves, etc. Thermal glove liners, worn under traditional gloves, serve a similar function as thermal shirts.