Best Base Layer – Expert Review

Updated: February 12, 2024

Base layers not only draw moisture away from the body, but also regulate your body temperature. Having a great base layer can be the difference between make or break when it comes to expeditions, so make sure you have the best one possible!

The MERIWOOL goes over and above for you pure, avid mountaineers. Known for its soft feel, this base layer is also super breathable which helps a lot in humid conditions.

If you are looking to save a penny or two, check out the Carhartt Lightweight Crew, starting as low as $25.

Whether it's hitting the slopes, climbing a face or running a trail, I'm a huge fan of the Under Armour Base 4.0 Crew for its 4-way stretch construction the helps you move better in every direction.

Best Base Layer (Top Picks)

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Best Base Layers For The Outdoors

(Detailed Reviews)

We reviewed over 12 base layers for this article. Below are the best base layers that made our short list.

  1. SmartWool Merino 250 Crew - Best Overall
  2. Carhartt Men's Force Lightweight Crew - Best Value
  3. Merino.Tech - Best Heavyweight Base Layer (For Cold)
  4. Under Armour Base 4.0 Crew - Best Technical
  5. Helly Hansen Lifa Stripe Crew - Best Lightweight

Read our complete buyers guide for base layers.

1. Best Overall Base Layer

MERIWOOL Mens Base Layer - 100% Merino Wool Midweight Long Sleeve Thermal Shirt Charcoal Gray

5/5 Overall Rating

The reason why we put our trust in MERIWOOL is because the 100% Merino Wool regulates temperature incredibly well, while eliminating the discomfort usually associated with wool. 

It is a versatile option, available for men and women.

We enjoy the fact that this layer provides an easy transition between weather conditions, from colder areas to areas that are warmer.

The slimline design gives it a nod above the rest, while being really comfortable and dependable.

With an excellent moisture repellant worked into the knit of the layer, you can understand why it keeps you dry and warm. 

It does provide significant UPF and can be used during a hike, or climb too. You can rest assured that working up a sweat is not a concern, as the material prevents odor build-up.

Main Features
  • Breathable knit to the Merino Wool fabric
  • Seamless knit and flatlock construction prevents chafing
  • Versatile design with good temperature regulation
What we like
  • Good performance layer that provides you with comfort, warmth, and breathability
  • Does not retain moisture 
What we dislike
  • Not a very durable option available
  • A rather costly pick, and sizing is a bit big
Key Takeway

The MERIWOOL is a reputable, dependable option. It is suitable for a variety of activities and works well on its own or under other layers. The concern would be its longevity.

2. Best Value Base Layer

Carhartt Men's Force Lightweight Stretch Grid Base Layer Crewneck Top, Black, X-Large

4.5/5 Overall Rating

The synthetic polyester material used in the construction of Carhartt Lightweight Crew provides breathability when you are on the move. 

The benefit of a synthetic option is that it is more durable than a 100% wool choice.

The fast drying capacity and gusseted stretch does not constrict but gives you the freedom to move around while protecting you from the elements. 

It is the warmest option and is better suited for activities requiring more rapid movement. So if you need an option that will remove moisture, dry fast have good packability, this is your pick.

The inclusion of flatlock seam designs, loops for your thumb, and a longer torso makes it a great choice for: layering and transferring moisture.

The satisfaction that this layer is a great option for women and men, puts it in the top of the charts too.

Together with the fact that it is less expensive than a merino wool option, it also has a choice of weight options giving you the freedom to invest in the one best suited for you.

Main Features
  • A weaved design suited for movement, and moisture removal
  • Thumb loops for convenience and a lower hemline at the back of the shirt, to ensure everything remains tucked. 
  • Breathable, quick drying design
What we like
  • Versatile option that layers well and can be used in the sun too 
  • A good price for the value it offers
What we dislike
  • It does not designed to provide a lot of warmth
  • Polyester is not as soft against the skin as wool
Key Takeaway

The Carhartt Lightweight Crew is a durable, lightweight option. It's perfect for layering in cold spaces, or single use in warmer climates. Its breathability makes the strenuous activities more comfortable, as your movements are not restricted.

3. Best Heavyweight Base Layer (For Cold)

Merino Wool Base Layer Mens - 100% Merino Wool Shirts for Men Thermal Underwear Long Sleeve T-Shirt for Hiking Hunting (X-Large, 165 Ebony)

4.5/5 Overall Rating

The flatlock stitching and integration of the design makes the Merino.Tech a winner for extreme cold conditions.

The 100% Merino Wool of this garment ensures that you remain warm and insulated throughout your trip.

Even though it is a thick option it still has really good breathability and the capacity to wick away moisture really well. 

You don’t end up sacrificing warmth for a breathable material. The wool is soft against the skin providing you with good comfort.

Together with its great warmth it also has good odor control because it pulls moisture away from the body instead of keeping it close to the skin.

However it isn’t the best solution for high-impact activities, where the heaviness of the material might end up being a liability instead of an advantage. 

A nifty thumb hole is included in the design, making sure that your hand is also kept warm which is a nice added benefit.

Main Features
  • The shirt is made out of 100% Merino wool
  • It provides you with great warmth giving you peace of mind in a colder condition
  • It is well-designed and fits the contours of your body
What we like
  • The design make sure that there's no chafing or friction giving you comfort during a journey
  • The structure and wool blend gives you a: soft to the skin feel
What we dislike
  • It's not necessarily ideal for high-impact activities because it's such a thick material it's best suited for the colder climates
Key Takeaway

If you are going on a really cold expedition it's best to choose the Merino.Tech because it is designed specifically for conditions that are tremendously chilly and you don't want to be left unprepared.

4. Best Technical Base Layer

Under Armour UA Base™ 4.0 Crew SM Black

5/5 Overall Rating

Quite an interesting mouthful, the Under Armour Base 4.0 Crew design has a blend of Merino Wool, polyester, and elastane in order to bring you the best of all the fabric worlds. 

The cosiness of the wool allows for softness against your skin, elastane and polyester ensures that moisture is not absorbed by the layer but repelled away from the skin.

Elastane enhances the mobility and comfort the shirt provides.

With good weather resistance you can use the Arc’teryx in wet, windy and dry conditions, giving you versatility and peace of mind.

The durability that it provides is found in the construction and design. It is breathable and robust, providing you with the security that it is not going to leave you in the lurch when the going gets tough.

Main Features
  • Blend of fabrics gives you superior quality and value
  • Quick drying design
  • The polyester gives you comfort and ease of use
What we like
  • The stretch material is durable and long-lasting
  • The flatlock construction in the seam prevents unnecessary friction and discomfort
What we dislike
  • Not the most breathable option
Key Takeaway

If technicality is what you are after on your trek, then the Under Armour Base 4.0 Crew is a sure win for you. The design blends the benefits of a variety of materials, providing you with a quality option for your trip.

5. Best Lightweight Base Layer

Helly Hansen Men's Lifa Stripe Crew Lightweight Breathable Moisture Wicking Thermal Baselayer, 998 Black, Large

4.5/5 Overall Rating

Helly Hansen Lifa Stripe Crew provides you with a budget-friendly option for your next trip. With the Lifa Fibre technique you are guaranteed to have a shirt that gives you significant breathability. 

Polypropylene fabric and Merino Wool blend give you a lightweight layer while providing insulation and warmth.

Construction of the shirt includes mesh panelling for ventilation and allows for moisture to be repelled away from the skin instead of absorbed by the material. 

The benefit of this technology means that your shirt does not get heavy when wet but remains comfortable throughout your journey.

Included in the design of the shirt means is a crew neck and that provides you with significant comfort and appropriate stretch for mobility.

It's breathability ensures that you are able to go the extra mile without feeling bogged down by the layers that you are wearing.

This shirt is versatile but does need some extra layers because it's not the warmest one available.

Main Features
  • Merino blend that has Lifa fibre in it to maintain the dryness of the shirt and wick away moisture
  • The shirt is versatile and cost-effective
  • Mesh panelling included in the design
What we like
  • A durable material that is breathable and lightweight
  • Activities that are high impact are best suited for this shirt
What we dislike
  • Doesn't provide as much insulation for colder conditions and is better suited for warmer climates
  • It does not have the best durability and is not as long-lasting as any other options
Key Takeaway

The use of Lifa fibre in the Merino blend of the Helly Hansen Lifa Stripe Crew ensures that your experience is breathable and enjoyable. You are provided with a long-lasting dry shirt during the high-impact activities, but it does need extra layering if you are in colder conditions.

Base Layer Buyer's Guides

It is advisable to consult the following guide to get a glimpse into the features that come together to provide you with a quality base layer.


The material of your chosen shirt is most likely: Merino Wool, nylon polyester or polypropylene. These materials are known to be durable, and breathable while providing you with significant comfort during a trip.

This allows you to get the full experience of the conditions and climate that you are in. With blended materials you are able to extract the benefits from all the materials instead of relying on the benefit of one.

Where Merino Wool is really warm and cosy, nylon and polyester offer a more durable, cost-effective way to stay warm. The benefit of elastane, that's usually included, gives your fabric more stretch which would help you when you are involved in more high impact, high mobility situations.

Moisture Control

Because of the nature of the activities that these layers will most likely be used in, it is advised that you keep moisture control in mind. This specifically aims to reduce how heavy the layer gets, and to ensure that it is able to dry quickly.

It is helpful if there is some kind of breathability or ventilation that the layer offers because it is usually worn under other layers, and you don’t want to be burdened by the number of clothing items you are wearing.

It is, thus, ideal to invest in a base layer that benefits your experience and works with, and for you, rather than against you. The degree to which your layer wicks moisture away is a crucial factor to consider especially if you are engaging in high-intensity activities.

The wicking capacity means that you do not feel the moisture retained in your shirt but that moisture is pulled away from your skin so that you are kept dry and comfortable.


The materials that work at repelling odor gives you the comfort of knowing that you're going to get a lot more wear out of your shirt. This is ideal if you are perhaps unable to wash it, often, due to extended trips.

Moreover, the comfort of knowing that your shirt dries quickly makes you aware of the fact that you're getting the best out of the option of your choice and gives you the peace of mind that the layer will not become a burden.


Additional features in the design of the layer gives you some practical, and functional components to think about. These elements include: longer torsos and hemlines so that it stays tucked in regardless of your movements.

It also includes thumb loops, for additional warmth for your hands. Slimline designs complement the contours of one’s body and give you a form fitting option for your convenience.

The loose-fitting shirts will lead to heat escaping, quickly, and that's important to know.

Depending on the activity you are engaged in would either call for these additional features or not, but there is a satisfaction in knowing that these features are made available, should you find yourself needing them.


About the author 

Mark Whitman

Mark has trekked extensively in Asia, Europe, South America and Africa. He founded Mountain IQ in 2014 with the sole aim to be the best online information portal to some of the most popular mountain destinations around the world. When not writing for Mountain IQ, Mark is out exploring the outdoors with his wife!

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