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Buying Guide: Baselayers

Want a bit of extra warmth on the mountain? Then baselayers may be the one for you! Baselayers and the art of layering is easy, if you know how to do it. We're here to provide you with a firmer grasp on what baselayers are and how to use them to create a versatile layering system that is comfortable, flexible and functional.

To help you choose what baselayer is right for you, we've put together this buying guide that addresses everything you need to think about when looking for your next baselayer.

Man & Woman Wearing Baselayers

What is a Baselayer?

A baselayer is, as the name suggests, the base of the layering system, and it is important to get the correct baselayer. You don't want to build on shaky foundations. Layering is the best way to keep warm. It is all down to personal preference, so what works for you may not work for someone else. Baselayers are designed to sit tightly next to the skin and wick moisture, such as sweat, away from the body. It is a far more effective layer than say an ordinary cotton t-shirt as it is significantly more durable, versatile and offers far greater warmth effectiveness than a single thick layer. Also, cotton retains moisture and doesn't work to move it away from the body, making it a killer when it comes to baselayers.

How Should a Baselayer Fit?

It is important that you select the right fit when choosing a baselayer. A poorly fitted baselayer can be uncomfortable and will ultimately be ineffective. As it is the nearest layer to your skin and the first layer, you will want a close fit as a loose one may cause skin irritation and bunching. The purpose of the baselayer is to help conserve body heat whilst wicking away any excess moisture, so the closer the fit the better.

Heavyweight baselayers are ideal if you want a looser fitting garment as they will still have a close fit but not as tight. The looser the garment is, the more air can flow between the baselayer and your skin, losing any heat.

Heavyweight baselayer fit

Baselayers come in a variety of different styles, each with its own benefits.


A baselayer top should have a tight fit. Use your standard t-shirt size when picking up a baselayer top as it will be snug by design, no need to size down to make it any tighter. You'll usually find baselayer tops with either short sleeves or long sleeves, however, you can also find some that boast a vest design for a cooler feel.


Baselayer bottoms are very similar in that they will also fit closely against skin to offer more warmth, but they are also very versatile to provide you with the highest amount of flexibility and ease of movement. Baselayer bottoms are perfect for snow sports, cycling and even under your normal clothes on colder days.

What Fabrics Are Baselayers Made From?

Most baselayers are made from either synthetic fibres or merino wool. Both of these fabrics optimise the bodies temperature in different ways and wick moisture to the surface, each with their own benefits and drawbacks in different situations.


Largely made from polyester or a polyester blend, synthetic baselayers are lightweight and usually the less expensive option as they use man-made fibres. Synthetic baselayers aren't as warm as their merino wool counterparts however they are still very versatile, making them suitable for sports activities such as cycling.

Merino Wool

Being the warmest of baselayer fabrics, Merino wool comes directly from merino sheep, so it possesses the natural ability to regulate your body temperature. It is naturally antibacterial, so it doesn't cling on to the smell of body odour, and also has UV protection. The only downside is that merino wool is that it is slightly more expensive than synthetic baselayers, however we find that the benefits outweigh the higher price tag.

Baselayer Materials

Baselayers also often come in blended fabrics as well, such as 50/50 synthetic-merino or 50/50 merino-primaloft.

How Much do Baselayers Weigh?

The weight of a baselayer determined the warmth that it produces. The heavier it is, the warmer it is usually. Generally, there are three different baselayer weights.


Designed to be worn next to your skin, this layer should be comfortable and must fit closely for optimal moisture management. It is ideal for cool conditions when there is a high level of activity involved.

Lightweight baselayer fit


Midweight baselayers can be worn as a warm first layer or as a second layer over a lightweight next-to-skin layer to maximise on its warmth capabilities. On its own it is ideal for cold conditions where a steady amount of activity is taking place.


Not typically worn as a first layer, Heavyweight baselayers are designed for cold conditions with any level of activity involved. Heavyweight baselayers tend to be paired with lighter materials, adding pure insulation, however, moisture management isn't a priority for these layers, so wicking properties are usually minimal.

The Importance of Cleaning Your Baselayers

It is important to keep baselayers clean for one main reason, odour. Baselayers typically absorb sweat and body oils during activity which builds up over time, leaving an unpleasant smell and a gross feeling to them. When baselayers aren't kept clean their performance gets impacted, and when they're not performing at their best, neither are you.

Luckily, Nikwax have you covered by providing high-performance garment cleaners specifically for baselayer that remove odours and prevent future build up. Pick up BaseWash for synthetic fabrics or WoolWash for wool garments. Finish off the process with some BaseFresh, a conditioner and deodoriser for all technical under garments, guaranteed to create a fresh feel in your baselayers.

Common Uses

  • Mountain sports – Skiers use baselayers to beat the cold climates of the mountains and control body temperature.
  • Cycling – Cyclists use baselayers to add extra warmth without adding any of the weight
  • Walking and Running – Perfect for wearing under shorts to offer warmth without any extra baggy material

Man stretching before run

Whatever you want to use baselayers for, we're sure you'll find them to be a fantastic addition to your outdoor wardrobe and you'll be blown away by how much extra warmth you'll receive from such a thin layer of clothing. We hope you find this guide useful, and if you'd like to pick yourself up some baselayers, head over to our store now and find a set that suits you!

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Ben is passionate about the beauty of the outdoors. Stargazing, sightseeing and outdoor photography hold a special place in his heart. Now that beauty is at risk he’s keen to take a stand to try and fight back against this Climate Crisis. In his free time, Ben is a music fanatic. If there’s one place you can find him, it’s at a festival. Plus, he plays guitar, bass and piano, as well as producing his own electronic & UK Garage tracks. He’s also a regular at every Wetherspoons in his local area, so if you ever see him around, pull up for a pint?

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