Trail-Tested Comfort: A Deep Dive into Helly Hansen’s LIFA Merino Midweight 2-in-1 Base Layer Pants

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Undoubtedly, Helly Hansen LIFA Merino Midweight Base Layer is among the classic models on the market of cold weather underlayer bottoms. This review is about this 2-layer performance base layer construction manufactured by the Norwegian powerhouse renowned for its expertise in designing and producing high-performance outdoor gear and apparel. Recognized for its innovative technologies, Helly Hansen (HH) is a trusted name among outdoor enthusiasts, professionals, and adventurers seeking reliable and durable clothing for harsh weather conditions.

The LIFA Merino Midweight Pant is a 2-in-1 blend featuring HH’s LIFA Stay Warm Technology on the inside for moisture management and quick-drying, and the natural insulation properties of merino wool on the outside. Marketed as a versatile multisport baselayer for extra warmth on cold days, we were eager to test its performance and see if it meets our expectations.

In the comprehensive review that follows, you will find detailed information about these base layer pants.

With a black Helly Hansen LIFA Merino base layer pants in the mountain forest

Quick specs: Helly Hansen LIFA Merino Midweight 2-in-1 Base Layer Pants

Price: $100

Weight: 285 g (10.05 oz) for ‘Black’ in men’s size 2XL

Material: 57% Merino wool, 43% polypropylene

  • Shell (exterior): Merino wool
  • Next-to-skin (interior): Polypropylene

Inseam: 31.5 inches

Where to get it: Amazon | Helly Hansen | REI | Backcountry

Notable features:

  • 2-Layer construction including 100% merino wool exterior and 100% LIFA – lightweight, moisture-wicking, and quick-drying synthetic fiber – next to the skin.
  • ZQ-certified merino wool material (ethical wool).
  • Flatlock seams minimize chaffing and discomfort.
  • Jacquard logo elastic waistband for functional convenience and comfort.
  • Performance stripes at bottom hem.


  • This midweight underlayer is warm and comfortable, with a great weight-to-warmth ratio. The thick, smooth, and soft stretch fabric provides an improved fit and generates extra warmth without itching. Overall, the base layer pants look and feel very comfortable.
  • Designed for optimal mobility without bulk, they are suitable for all kinds of cold-weather sports and activities. Versatile, the bottoms can be used for a range of pursuits including hiking, backpacking, mountaineering, skiing, and snowboarding as well as everyday wear and work.
  • With a classic design, the fit isn’t too tight or overly loose. Just make sure to get the right fit as this underlayer tends to run larger than nearly all other Helly Hansen base layers we’ve ever tried in the last several years.
  • Excellent breathability and moisture-wicking abilities. The superior thermoregulation they provide makes the pants super comfortable, during a variety of physical activities, even when wet (you won’t even notice it before you take off the pants). This works super cool for sports and activities where because of the higher intensity/exertion (hence extra sweating), your base layer pants will inevitably get wet.
  • The natural antimicrobial properties of merino make it suitable for long-duration wear. Doesn’t need washing after nearly every use as is the case with all-synthetic alternatives.


  • Ideal for cold to cool weather activities only. This thermal layer provides extra insulation, generating warmth that will be too much for milder weather.
  • The merino-polypropylene material holds up well, but proper care is more time-consuming and requires extra effort. We strongly recommend following the manufacturer’s instructions to prevent shrinking or stretching of this long underwear. Proper care and maintenance are key to ensuring the longevity of such a technical garment.
  • Takes longer to dry because the thick material needs more time to dry completely. Additionally, as with other merino wool garments, it is advisable to let them rest for at least 24 hours after washing/drying before using the pants again.

Women’s Version: Available -> Amazon | Helly Hansen | REI | Backcountry

Wearing black bottoms and a top in the late winter
This base layer bottom is perfect for winter as well as early spring and late fall


We got these technical multisport base layer pants in early March and have been testing them since then in various temps from as low as -7 to -5°C (19-23°F) to 12°C (54°F) in both dry and wet weather. What’s also important to mention is that they’ve been tested in a multitude of conditions and environments including during hiking trips in various settings (mountains, forests, fields), as well as casual wear in town.

Versatility is of paramount importance for a piece that’s expected to work as a part of a layered clothing system without adding unnecessary bulk. The merino-LIFA blend is soft, has an itch-free feel, and offers a great combination of warmth and moisture-wicking properties for keeping sweat away from the body to prevent chilling when playing in cold conditions. The adequate breathability prevents overheating during physical activities.

The quality of both the material and construction are impressive and we’d lose no more time to introduce you to the LIFA Merino Midweight 2-in-1 pant in detail, its pros, cons, features, and uses as well as its performance and functionality across different environments.

Detailed review

Material, construction, and durability

The overall construction is well-made and we really like the attention to detail demonstrated by the guys from Helly Hansen. The material and craftsmanship are of visibly high quality.

Much like the LIFA ACTIVE design, this underlayer is built as a 2-layer construction, comprising a merino wool exterior and a LIFA interior. The exterior is crafted from 100% merino wool because of its superior insulative properties that make it a valued material for cold weather clothing and especially activewear. The next-to-skin part is crafted from 100% LIFA.

The merino wool is ZQ-certified meaning that it is sourced from sustainable. The LIFA Stay Warm Technology is Helly Hansen’s unique fiber (essentially, modified polypropylene). Designed to provide insulation, exceptional moisture management, and comfort for both outdoor activities and everyday wear, this technology is a core element in many of Helly Hansen’s baselayers, serving either as a primary component or in a supporting role.

Each of the materials utilized for this base layer does its part well. So far, the garment has been washed several times, and it looks and feels like brand new. The fabric is very soft and there are no signs of wear or deterioration, except for some minor pilling.

Weight and packability

While the product page shows 350 g (12.35 oz), the weight we measured is 285 g or 10.05 oz for ‘Black’ in men’s size 2XL. The box is labeled 225 g, but apparently, the garment inside is much heavier. It isn’t the first time we found a discrepancy between what’s the weight according to the dedicated HH’s product page and the real weight of a product. A quick reminder – the LIFA ACTIVE base layer top whose weight is 270 g or 9.52 oz according to its product page turned out to be a mere 185 g (6.53 oz) for size 2XL.

The package box of the HH LIFA Merino
This multisport baselayer doesn’t weigh 225 g, despite what’s written on its box

As we already mentioned, 2XL is the largest size offered by Helly Hansen for the LIFA Merino Base Layer Pants. How do these 285 g compare to the weight of other top-quality merino underlayer bottoms? The weight of the Smartwool Classic Thermal Merino Base Layer Bottom also known as Smartwool Merino 250 is comparable to the weight of the HH LIFA Merino. With a similar weight (272 g or 9.6 oz for size Large) comes Minus33 Kancamagus. Another serious contender for cold weather sports and activities, Icebreaker 200 Oasis Leggings with Fly comes at 199 g or 7.01 oz (for size Medium). Another lighter model, REI Co-op Merino 185 has a similar weight as it comes at 210 g or 7.4 oz (for size Large). The heavier Icebreaker Merino 260 Tech is an excellent option for cold weather layering coming at 270 g or 9.51 oz (for size Medium).

The garment is quite packable, making it easy to carry and store in your backpack for whenever you need it during a longer trip. It takes up a bit more space than all-synthetic baselayer pants (weighing 100 grams less) and is only half the volume of a comparable mid-layer like the Daybreaker.

Design, fit, and comfort

Mobility is easy with this underlayer
Mobility is easy with this underlayer

There are a few details that we think are important for the overall reliability and comfort of this particular construction:

  • The first one is the classic design. It prioritizes freedom of movement, allowing for optimal mobility during outdoor activities, sports, or any situation where flexibility is essential. There’s no unnecessary bulk (except for the potentially excessive material around the ankles and lower legs), which facilitates layering and feels much more comfortable than wearing bulky layers that can restrict movement and comfort.
  • The soft and stretchy fabric feels very comfortable providing a pleasant feel against the skin. This not only enhances the overall comfort but also allows for excellent flexibility and ease of movement. Additionally, the close contact with the skin traps and retains body heat in colder conditions
  • Adaptable to both low and high-intensity pursuits, the bottoms can easily transition between various activities and weather conditions. We find them sufficiently comfortable for both cool-to-cold dry and wet weather.
  • The double stitching adds extra strength to the construction, and with fewer seams and embellishments, there’s less chance of wear and tear. This ensures that the undergarment can handle regular use.
  • The flatlock seams minimize chafing. This reduces discomfort but also enhances the overall durability and longevity of the garment.

The garment isn’t too tight or overly loose – it’s just the right fit. This comfortable fit is essential for all-day wear, preventing discomfort or irritation during various activities. Make sure to get the right fit for yourself. The size you see in the pictures in this article is 2XL. There are five size options available as Helly Hansen offers these underlayer pants in size options from S to 2XL for the men’s version and from XS to XL for the female’s version. So 2XL is the biggest size for this particular design.

Now, ask me if it is okay for a person who’s 186 cm (6’1″) tall and weighs approximately 96 kg (the weight of the author varied between around 96 kg and 101 kg or 211 lbs to 223 lbs between March and December). Long story short, it was huge initially. So, no matter what they say, this one runs large – actually, it’s the largest HH base layer I’ve ever tried. Just for a comparison, its overall length is approximately 10 cm (4 inches) longer than the length of the LIFA ACTIVE base layer pants (2XL, the largest size of this model). Don’t know why, but had the impression that I would need the biggest size and made this mistake. Again, 2XL in this design should be suitable for someone who’s like 2-2.05 m (6’7″-6’9″) tall and weighs 110-120 kilos. Of course, as the fit is influenced by factors like height, weight, and body shape, this is just a speculation.

Ensure that you carefully review the sizing chart before placing your order to avoid any unnecessary issues. The good news is that Helly Hansen has a ‘Find Your Size’ button (it shows that XL size should be best for me) on their website’s product page, and it’s available for most of their offered products. According to Helly Hansen, customers report that the fit is ‘True to size’, but we can argue on this. In any case, correcting (hint: shrinking) a base layer that’s one size larger can be feasible depending on the material it’s made from, and that’s precisely what we did.

Potential friction points (for those with sensitive skin) are the labels inside. There are 3-4 labels, and if you want, you can remove them to avoid irritation. For your information only, we still haven’t removed them as we haven’t found them to be unpleasant or uncomfortable.

Warmth and layering

This base layer bottom is specifically designed to provide superior moisture management and warmth in colder conditions. Keep this in mind. We recommend using it for temperatures below 10°C or 50°F, especially below 5-6°C (41-43°F). This means that this long thermal underwear is generally suitable for winter, as well as cool spring or autumn days. We tested it in temperatures as low as -7°C to -5°C or 19-23°F (paired with softshell pants). When staying active, we felt cool but not cold, which felt normal and acceptable. However, if you’re not staying active, feeling cold is inevitable, and this combination won’t provide enough warmth. Fortunately, the base layer pants are easy to layer up with other garments for colder weather. During brisk hiking in slightly higher temperatures ranging from -2°C to 1°C (28-34°F), wearing these bottoms with lightweight hiking pants like the KUHL Renegade felt comfortably cool, preventing heat build-up.

You will notice that the length of the legs is excessive unless you are 2 m tall (specifically for the garment in size 2XL). While it may seem a bit strange at first, the extra material is easy to adjust around your ankles and lower legs. This shouldn’t hinder the ability to layer up.

Leg length comparison - unaltered (left) and adjusted around the ankle (right)
Leg length comparison – relaxed (left) and adjusted around the ankle and lower leg (right)

Once the thermometer reaches 10-12°C (50-54°F), especially during brisk walking, hiking, or other moderately intense activities, wearing these bottoms even with lightweight hiking pants may start to feel uncomfortably warm. However, for casual walks and less active situations, you can comfortably wear similar combinations without experiencing constant sweating.

Breathability and ventilation

While the material is fairly thick, the material and weave allow the LIFA Merino base layer pants to breathe effectively without being airy like a mesh.

We like that this underlayer allows excess heat to escape when the body is active and provides sufficient insulation when the wearer is less active. This makes it an excellent choice for outdoor activities in cold to cool temperatures (in various weather conditions), where sweating typically isn’t as problematic as in milder temps. We gotta mention, that we didn’t really notice any major changes in how breathable it is while trekking through constant rain for hours (in cool-to-cold and wet conditions). Now, if it’s rainy or windy, our suggestion is to team it up with a pair of wind and water-resistant pants. Why? This underlayer works great in still weather, but it will struggle without that extra layer of wind and water resistance.

For higher temperatures, you won’t need more than a pair of hiking pants or a combination of pants and a lightweight base layer. A thicker and heavier garment like the Helly Hansen LIFA Merino won’t provide sufficient breathability and ventilation in such conditions.

The airflow cools the legs, improving comfort and assisting in regulating body temperature. But, we’ll dig deeper into this in the next section, as effective moisture-wicking management plays a key role in maintaining the right body temperature.

Moisture management and drying speed

Merino wool has excellent moisture-wicking properties. In these bottoms, it is combined with a next-to-skin LIFA (polypropylene) layer – engineered specifically for outstanding moisture-wicking capabilities, designed to keep the skin dry during various activities. This is a typical combination by Helly Hansen used for high-performance multisport base layers.

The performance is first class. There aren’t many undergarments out there that can do it as efficiently. The effective wicking of sweat away from the skin and its transport to the outer layer for quick evaporation keeps the skin dry and prevents chafing. This ensures you stay dry and comfortable, even during high-intensity activities.

Most of the time, sweating is not a problem, as the typical sensation of damp skin when wearing all-synthetic base layers is barely noticeable, and only occurs if sweating excessively. This is great for cold weather when sweating can be not only uncomfortable but also undesirable.

In addition to the moisture-wicking abilities, the natural antimicrobial properties of merino help reduce odor. This means you can wear the pants for longer without worrying about them becoming smelly. Thanks to the natural odor resistance, airing your garment for a few hours outside will keep it fresher for longer instead of washing it after each use. This trick will not only save you money (water, detergent, and electricity), but will help the merino wool material keep its properties for longer.

Of course, from time to time, you should wash the garment. Just follow the manufacturer’s washing and drying instructions, and this should be sufficient to prevent the pants from shrinking or losing their shape. Merino requires delicate care to maintain its quality and performance. Knowing this will help you keep the LIFA Merino base layer in good condition for longer. This would be a drawback for those who prefer a low-maintenance underlayer that can be thrown in the washing machine and dryer without worrying about it shrinking or losing its shape.

The drying time of the fabric is longer than that of typical synthetic materials used for underlayers (polyester, polypropylene, etc.). This is due to the wool, as it tends to retain more liquid when wet. This means that if you sweat heavily or get wet, it will take a while for the pants to dry completely. While in normal circumstances it won’t be a problem, this can be a serious disadvantage if you need to change clothes quickly, especially in cold weather.

In a combination with lightweight hiking pants
Matching it with suitable hiking pants is essential if you want to feel cool and comfortable on the trail


The heavy price tag of $100 (similar to the LIFA Merino Midweight Crew Top) might seem a bit too much for those who are not accustomed to investing in and wearing similar designs. However, this price makes the LIFA Merino quite competitive compared to other high-quality base layer bottoms with similar features. When on sale, you can hope to find it for as low as $50-$70.

To provide you with a comparison to other merino base layer designs, here are some of the best underlayer bottoms available on the market today.

Smartwool Classic Thermal Merino Base Layer Bottom is a classic midweight merino wool undergarment. Made with high-quality 250-weight Interlock-knit merino wool, this underlayer is known for its excellent breathability, comfort, and no-itch feel. Not too light or too heavy, these thermal pants have it all to keep you warm outside with minimum chaffing thanks to the flatlock seams. While these are 100% merino wool, we consider them among the closest competitors to the HH LIFA Merino both in terms of comfort and functionality. Generally, the Smartwool Merino 250 bottom costs $115, yet it can be found for around $80 or so when on sale.

Icebreaker 200 Oasis Leggings with Fly and the heavier and pricier, and even more suitable for cold weather Icebreaker Merino 260 Tech Thermal Leggings with Fly are all-merino base layers that come with a contoured pouch with fly for convenience, flatlock seams for preventing friction, and a gusseted crotch for enhanced mobility. Soft, warm, comfortable, and versatile for a variety of outdoor activities in cool-to-cold weather, although not the most durable option available. With a price tag of $105 and $125 respectively, these designs are good alternatives to the Helly Hansen LIFA Merino.

Minus33 Kancamagus Midweight Bottom is a versatile underlayer made of high-quality merino wool. Designed to provide warmth and comfort throughout the day as a part of your cold weather layered clothing system. The fit is bulk-free, making layering easy. The odor resistance of merino wool ensures these won’t become stinky after use on and off the trail. The usual price is around $105.

REI Co-op Merino 185 Base Layer Bottoms is a slightly more budget-friendly option that usually comes at $79.95 (but can be found for as low as half of that on sale). It has many features typical of premium base layer pants, though it doesn’t have the best quality and build. The fabric is soft and comfortable, and it’s versatile so you can wear it in various conditions. The thinner merino material can be a concern as long as durability is concerned. Priced and sized right, it offers a reasonable choice for those on a budget.

Meriwool Merino 250 Base Layer Bottom is a good midweight option for those who are on a tight budget as the typical price of these bottoms is around $60. The soft interlock-knit merino wool has a 250 g/m2 weight, typically sufficient to provide proper warmth while staying active in cold weather. It isn’t itchy and offers comfort. Fitted for easy layering, it’s an overall good product given the more affordable price. However, you cannot expect these to be as good as the HH LIFA Merino, Smartwool Classic or Icebreaker Oasis.


In conclusion, the Helly Hansen LIFA Merino Midweight Base Layer Pants have proven to be a high-performance and versatile choice for outdoor and multisport activities. By combining the natural insulation and warmth of merino with the advanced moisture-wicking technology of LIFA, these bottoms offer optimal comfort and protection in cold weather. The classic cut, flatlock seams, and soft, itch-free material contribute to minimal chafing and discomfort. This, along with premium construction, ensures optimal mobility without bulk.

The focus on comfort, warmth, and moisture-wicking capabilities ensures a pleasant experience in various settings, as long as the weather is cold to cool. We believe that these base layer pants are an excellent option for those seeking reliable performance across different conditions and activities.


Related Articles

Helly Hansen LIFA ACTIVE Base Layer Pants Review

Helly Hansen Daybreaker 1/2 Zip Review

KÜHL The One Hoody Review

Helly Hansen HH LIFA Merino Review

Smartwool Hike Full Cushion Crew Socks Review

Smartwool Hike Light Cushion Crew Socks Review

Smartwool Hike Light Cushion Ankle Socks Review

KÜHL Renegade Review

Helly Hansen LIFA ACTIVE Crew Review


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