Warmest Base Layer: Reviewing the Best Base Layers You Can Buy

Best warmest base layers
Russell McCarty
Written by Russell McCarty

Unlike many other types of clothes, finding the warmest base layer is easier. This is because all we need to do is to look at the type of yarn used and its properties. Learning more about why and when people consider putting more clothes on will help with making an informed and better decision regarding the piece of clothing you’re about to purchase.

It is common knowledge that layered clothing insulate better against the cold weather, than a single and thick garment. This is the main reason people choose this way of dressing in autumn and especially winter. Layering is also recommended for when people go hiking: when they’re too hot they can easily remove one layer without ending up completely uncovered.

Ski Best Base Layers

Before we continue, remember that you can also use the term “inner layer” instead of “base layer.” The terminology implies that all the other garments come on top of this one.

Let’s talk about the fibers of a base layer garment

The best base layer for cold weather must be able to absorb the body’s moisture, allow it to evaporate, and not retain smells. Furthermore, the texture of the fabric has be soft because this layer usually comes in direct contact with the skin. It is clear nobody wants to wear clothes that feel damp, or that cause itching.

Warm layer clothing

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This takes us to the next part of this presentation: fibers used the most for base layers. There are two major categories: natural and artificial. The natural fibers are cotton, wool, and silk. The artificial ones are: polyester, polyethylene, and microfiber.

  • Cotton absorbs moisture well, however it has the tendency not to let it evaporate. This is particularly true when other clothes and fabrics come on top of cotton. People like cotton as a base layer because it is comfortable and pretty pleasant against the skin. Cotton is best worn during the warmer months.
  • Wool is well known to give an itching sensation, but with today’s technology this is a problem of the past. Merino type of wools are particularly popular and in high demand for many types of clothes, including inner layers. This fiber insulates well and also removes sweat rather easily and doesn’t remain damp.
  • Silk fabrics are known to cool the body down, and this is why the best summer sleeping garments are made out of this material. Caring for or cleaning silk is also difficult and usually best left to the professionals. It is pretty clear that nobody will wear garments made of silk in winter anyways.
  • The synthetic fabric, no matter their type, are notorious for drying quickly, but also for their tendency or retaining or starting to smell bad. Nowadays, these materials receive treatments with anti-bacterial agents to reduce smells and to even repel insects.

Price-wise, wool and silk are the most expensive fibers while the artificial ones are the cheapest. All these fibers can mixed together for their qualities. The resulting yarns can be more affordable, last longer, and be very pleasant to the touch. These days, most base layers use a fiber combination to deliver the best results.

Most clothes made of natural fibers can’t be recycled into other garments, because the resulting fiber will be too short and more fragile. Natural materials are usually turned into other items, such as carpets for instance. On the other hand, synthetics can be turned back into clothes. Usually the recycled material is mixed with brand new fibers, no matter their type.

When can or should I wear my base layer?

This question was only partially answered before. Most people use an inner layer in winter or when they travel to really cold locations. However the current design of these garments allows you to wear them even in spring and autumn when going for a run or a bike ride. During the warmer months, you will definitely not need anything over this top unless you go camping, hiking, or climbing mountains.

Ski base layers used by skier

You should also know when not to wear clothing as base layers as well. Generally speaking, if an item doesn’t allow the sweat to evaporate, then don’t wear it as inner layer but as a mid layer instead.

Various features of an inner layer

The first thing you’ll notice about all items that can be labeled as such, is that they all have long sleeves. This is especially true for the clothing items made for winter. Some might have a shorter sleeve, but those are not recommended for really cold temperatures.

Sometimes the sleeves have loops for the thumb fingers. These holes help with keeping the sleeves over your wrists during acts of climbing and the like. Clearly the sleeves are longer in this case, and protect better against the elements.

Inner layer clothes may or may not have a front zipper. If they do have one, it will not run all the way down like on a cardigan, but it will stop mid-way down, at your solar plexus. At times, the zipper can be half as short. The garments with a zipper have a really tight neck hole and perhaps a bit of a collar as well.

Baselayer with Down Sweater

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The lack of a zipper indicates a larger neck hole and perhaps even the absence of a collar. Clothes makers should pay attention to the zippers they choose for it will directly touch the skin and it can disturb the wearer.

What will probably surprise you, is the lack of pockets. Since these tops are meant to be worn under at least one other layer, accessing the pockets would be difficult, therefore the garment doesn’t need them.

You’ll also notice how most of these tops fit just right, if not a bit tight around the body. While they’re tight, they’re not restrictive, but allow all sorts of movements. In most cases, these tops fall right at the hip area. Some models have a longer back compared to the front, for a better coverage.

Ski base layers

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It’s not uncommon to find base layer tops that can be worn by both genders, but gender specific items are rather popular. Those that specifically made for women might have brighter colors and designs with flowers. They will generally be too small and tight for a guy to wear.

Taking care of this clothing piece should be easy as generally they can be washed in the machine. Depending on the fiber type, a gentle cycle is preferred. Furthermore, drying should be done using the old fashioned method of handing the clothes to dry. This process takes place rapidly and will ensure the item doesn’t shrink or lose shape.

Now that you learned almost everything possible about the base layer, you can take a look at some of the warmest on the market. Our selection includes garments for women, men, as well as unisex items, giving you plenty of options.

The best base layers to keep you warm

Helly Hansen Freeze Shirt

Weight: –Helly Hansen Women's Warm Freeze


Size: XS, S, M, L, XL

Features: Good insulation and moisture management

Best for: Ski trips, hiking

This Helly Hansen Freeze Shirt has a very short collar that stays close to the neck and some wearers might feel strangled. This feeling can be reduced by undoing the short zipper that is nearly invisible. The top is soft and comfortable enough that you can wear it directly on your skin. The major downside of the garment is that it runs small and you have to order at least one size bigger than what you usually wear.

There are some women who are not happy with theirs arms, and this top can help as it has longer sleeves making your arms appear longer and slimmer. If you wash it according to the instructions, this garment will not deteriorate nor lose shape.

What’s more is that it dries really fast as the fabric is made not to retain moisture. If you have been sweating and don’t have the means to wash your clothes, all you have to do is to hang this piece in a well ventilated place and any smell will be gone.

Related: The Active Flow top by Helly Hansen has a taller and a bit larger collar, giving less of a strangling sensation even when fully zipped.

Check the price on Amazon

Marmot Thermal Top

Weight: 6.2 oz (175.8 g)Marmot ThermalClime Pro Crew

Dimensions: 29.5 in (Center Back Length)

Size: M

Features: Lightweight

Best for: Camping, hiking, running

There are many people out there complaining their clothes don’t fit as they should or as expected, not even when buying the right size. This is not the case with the Marmot Thermal Top. The sleeves are a little longer to offer better coverage when stretching your arms while hiking for instance. This top doesn’t have a zipper making it more comfortable for everyday wear and you can do so without having to wash it too often.

The garment is made using Polartec Power Dry technology that helps with reducing body moisture and odor, as they form. The  fabric also doesn’t retain water nor shrinks –  a feature that helps with the item maintaining its shape and quality for a longer period of time.

Many clothes have tags at the back of the neckline and sometimes this can be disturbing. You can forget all about being uncomfortable with the tags or having to cut them off, because this Marmot garment doesn’t have them.

Check the price on Amazon

Mammut Long Sleeve

Weight: 145 gMammut Go Warm Zip Women's Longsleeve

Dimensions: –

Size: XS, S, M, L, XL

Features: Thumb hole, breathable, unisex

Best for: Backpacking, alpinism, ski touring, backcountry skiing

A good base layer can go a long way and be used for many different purposes. This Mammut Long Sleeve can be used not only or the above mentioned activities, but for running or jogging as well. The thumb loops help with keeping the sleeves in place when performing specific movements and activities such as alpinism.

Additionally, it helps with keeping your wrists and hands warmer when skiing, especially if you feel your gloves don’t do the job right. The top is made of a combination fiber of wool and a special type of polyester that improves breathability.

You will not overheat, but at the same time you won’t feel cold either. This is due to the ability of the fabric to let body moisture evaporate at a rather fast rate. Some garments are specifically tailored to the needs of one gender or the other, but not this top. This top can be worn by both genders, which can be convenient in some cases.

Related: The garment we just presented has a regular fit. If you want a tight fit, check out the Mammut Atacazo Light Zip Pull, that also has a longer zipper on the front.

Check the price on Amazon

Icebreaker Oasis Crewe

Weight: 12.2 ouncesIcebreaker Men's Oasis Long Sleeve


Size: S, M, L, XL, XXL, XXXL

Features: Lightweight

Best for: Summer hiking, winter sports

If you need a shirt that you can wear without washing for a longer period of time, then this is it. Made in totality of Merino wool, you now know why we said this. This type of wool simply doesn’t retain smells as easily as other fibers and is one of the best insulating material out there.

Natural fibers have the tendency to shrink when cleaned the wrong way, so follow the instructions if you want a long lasting garment. You probably already know how some clothing items get holes after a few washes, and then the garments simply falls apart. This happens with lower quality fabrics, but not with this Icebreaker Oasis Crewe.

This garment is soft, comfortable and can be worn for several days in a row without any hint of a bad odor – just make sure to hang it out overnight in a place with a lot of fresh air. It is possible that taller people will find the garment short, so it might be better to buy a larger size which will also be longer.

Related: The Icebreaker Crewe is a good alternative, although the design is almost identical.

Check the price on Amazon

Mountain Hardwear Long Sleeve

Weight: 6 oz (170 g)Mountain Hardwear Integral Pro Long Sleeve T

Dimensions: 25.5″ (65 cm) middle back length

Size: S, M

Features: Thumb holes

Best for: Running, cold weather

Leading a fast paced lifestyle means not everyone has the time to hand wash clothes or to wait for them to get dry. This Mountain Hardwear Long Sleeve makes the cleaning process much more easy and fast, as all you need is a washing machine with a gentle spin.

However, given the wool in this garment, it is recommended you let it air dry, as it will do so rather fast anyways. We all have a pet peeve when it comes to clothing, and one of these could be the sleeves that don’t stay put. The thumb loops on the sleeves of this top will ensure your wrist stay warm and covered at all times, and that the sleeves will not slide down when you reach up.

The top has a zipper in the front so that you can put it on with more ease. There are also at least two colors to choose from, to better define your style and personality.

Related: If you want something with a hood, maybe the Mountain Hardwear Integral Pro is something you could be interested in.

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SmartWool PhD NTS Light

Weight: –Smartwool Men'S PhD NTS Light

Dimensions: 12 x 10 x 1 inches

Size: M

Features: Form fitting, lightweight

Best for: Multisport

If you’re an active person you most likely need at least one form fitting tops that has long sleeves. This SmartWool PhD NTS Light could be a good addition to your closet as it is made mostly of Merino Wool. The wooly part are on the back and the sleeves and this is an important feature because your body will sweat when you work out, but the wool won’t smell and will let your body breathe.

As the name suggests, this garment has a half zipper on the front to facilitate putting it on and taking it off, while giving you the option to let it unzipped if you need to feel extra refreshed. The front of the garment uses a windproof fabric – very useful when you run in windy weather wearing just this. You can safely wash this clothing item in a delicate machine cycle and have it air dry rather quick. It won’t lose shape either, like many others do.

Related: The ladies can try out the Smartwool Womens PhD Top for when they want to work out in colder weather.

Check the price on Amazon

Some Parting Words

The above garments are perfect for layering in winter under a few other clothing items if you’re more sensitive to lower temperatures. They can also be worn on their own in shoulder seasons, or when it’s too warm for layers but too cold for T-shirts. Both men and women can use this type of tops as seen from our selection. These can be worn for many different purposes, including camping, hiking, and simply running in the park.

We’d like to hear if you have any experience with any of these tops or if there is any other that keeps you warmer than these.


Russell McCarty

Russell McCarty

Russell considers backpacking one of his great passions in life. He actually managed to transform his passion into a living becoming a professional adventurer. Russell loves long-distance backpacking and he enriched his portfolio with famous trails like the Alaska-Yukon Expedition or the Appalachian Trail. With thousands of miles under his feet, Russell is the expert to consult when it comes to how to prepare for a successful outdoor adventure.