Best Merino Wool Base Layer: All About That Base

Merino 365 New Zealand 100% Merino Longsleeve Baselayer with Thumbloops
Written by Russell McCarty

Layering wasn’t just the look of choice for those of us who lived through the grungy 90s; layering is essential when it comes to maintaining ultimate comfort and performance on the trail. Being able to add and remove layers is a necessary part of adjusting to the fluctuations of climate and body temperature during a day in the wilderness, and establishing a solid base layer is one way to get started off right.

There are a wide variety of base layer materials available today, including polyester, nylon, cotton, silk, but we’re going to be taking a look at one of the most popular and high-performing materials when it comes to outdoor wear: merino wool. All natural and lauded for its many activity-friendly features, merino wool is the perfect foundation for building an outfit that will have you feeling just as fresh at the end of your hike as you were at the beginning.

We’ll examine some of today’s top choices available so you’ll be sure to choose the best merino wool layer possible to suit your plein air adventuring.

Base Layers: Know What’s Up Before You Buy

Drilled down to simplest terms, a base layer is the first layer of clothing you wear. It has direct contact with your skin, which makes fabric choice key in avoiding caustic chafes and raging  reactions. A good base layer should manage moisture, protect your skin, and maintain a comfortable body temperature. Because of its high marks in all these areas, merino wool has a significant amount of clout as a base layer.

But why are these characteristics so important, and how exactly does merino wool address each of them? Well, we’re glad you asked:

Moisture Management

If you’ve ever layered poorly before strenuous activity, then you know the supreme discomfort of having a soggy, sweaty shirt clinging to your skin. A wet base layer is bad news all around: it causes you to lose heat and also makes you more prone to chafing, not to mention it just feels gross.

Merino wool is excellent at soaking up moisture—it can absorb up to 33% of its own weight in water—so even if you sweat up a storm on the trail, your skin will be kept as cool and dry as possible as the merino wicks moisture to the outside of the garment to be evaporated clean away. The only thing to be forewarned about when it comes to merino and moisture is that once merino gets honest-to-goodness damp, it can take longer to dry out than synthetic fabrics.

Pro-level Protection

Perhaps one of the most impressive features of merino wool is that it naturally absorbs the sun’s  radiation throughout the entire UV spectrum. Merino garments don’t have to be treated with special protectants like other fabrics; the natural qualities of the wool take care of it automatically. That’s probably why you’ve never seen a sheep by sunscreen, and definitely why merino wool is an all-star base layer when in comes to keeping your skin safe.

Temperature Control

Going hand-in-hand with merino’s mastery of moisture management is its natural adeptness at regulating temperature. Each merino wool fiber has a water-repellent outer core and water-absorbing inner core, which means that moisture is quickly transferred to the inner core while the skin-facing outer cool stays dry, making you feel dry and, therefore, warm.

You can always remove a wet fleece or jacket, but base layers need to stay put, which is why it’s essential to wear one that can stay dry and warm even when conditions are cold and damp.

Supervisors of Stink

Because they’re the layer next to your skin and therefore next to all the…magic your body makes during physical activity, you’ll want a base layer that’s equipped to handle odor. Merino wool is naturally resistant to odor, ensuring that the only thing you’ll smell on the trail is fresh air. Merino base layers can be worn for days without washing, making them perfect for a days-long hiking trip when you want to keep your pack light (and your personal perfume at bay).

Top Merino Wool Base Layers You Can Buy

Now that we’ve made the case for merino, let’s take a look at some high-rated options when it comes to choosing the best merino wool base layer for you.

Ibex Woolies Zip T

Weight: 9 ounces

Dimensions: 10 x 5 x 4 inches

Specific features: This 100%, 18.5 superfine merino wool (150 g/m2) base layer offers a close-to-the-body fit, award-winning ribbed fabric, flat lock seams, wide cuff detail, set in sleeves, 9-inch zip neck with locking pull. The Rib construction for optimal breathability, and is machine washable.

Best use: The Ibex Woolies Zip T is a durable base layer for cold weather running, cycling, or hiking and can even be worn alone on warmer days.

The Ibex Woolies Zip T is an expertly constructed base layer designed to move with you and keep you comfortable from the first seconds of activity all the way through until the end of the day. The 100% superfine merino wool provides ultimate comfort next to your skin, wicking away moisture and handling odors with ease. The award-winning ribbed fabric and “He Rib” construction provides custom fit and breathability, and ensures that this base layer will stretch along with you without ever losing its shape.

Users report that this base layer is a smart and fashionable choice to be worn for high-level activity or just to stay toasty and covered while running errands around town. Don’t let the featherweight nature of the Ibex Woolies Zip T fool you—it may feel light, but this popular base layer shirt offers some heavy duty protection from the elements.

Related: The Ibex Women’s Racerback Shirt is made of incredibly soft, lightweight wool and is designed to keep you dry and comfortable no matter where the day takes you.

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Mammut Go Warm Zip Long Sleeve

Mammut Go Warm Zip Women's Longsleeve

Weight: 5 ounces

Dimensions: –

Specific features: This high-performing base layer features an efficient blend of 78% polyester and 22% merino wool, a tailored fit, and extended back piece to protect from chilly winter air.

Best use: Perfect for cold weather activities such as backpacking, ski touring, backcountry skiing, and mountaineering.

The Mammut Go Warm Zip Long Sleeve combines functionality consumers demand with the pleasing aesthetic design they enjoy. The contoured cut of this base layer is flattering and thoughtful; the extended back piece ensures that your lower back will stay covered as you cycle, climb, or even wipe out on the slopes. The Mammut Go Warm Zip Long Sleeve features a blend of both merino wool and polyester to give wearers the best of both worlds in terms of heat retention, moisture wicking, and odor resistance.

The use of a blended fabric also allows this top to dry more quickly after laundering or rinsing. The Mammut family prides themselves on the thorough design and consideration that goes into making every garment, and their signature poly-merino blend was carefully analyzed and re-analyzed to produce a finished product that even the most seasoned outdoor adventurers (and die-hard merino enthusiasts) will find to be the pinnacle of comfort and performance.

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Merino 365 New Zealand Longsleeve Baselayer

Merino 365 New Zealand 100% Merino Longsleeve Baselayer with Thumbloops

Weight: 8.2 ounces

Dimensions: –

Specific features: This extremely popular base layer is made from 100% New Zealand merino, is machine washable in cold water, and sports convenient thumbloops.

Best use: The versatile Merino 365 New Zealand 100% Merino Longsleeve Baselayer is perfect for any outdoor activity, from hiking to skiing to climbing.

Merino 365 New Zealand Longsleeve Baselayer is a beloved staple in the wardrobe of many adventurers who don’t let the weather stop them from hitting the trail, the stream, or the slopes. Crafted from 100% New Zealand merino wool, this incredibly soft shirt boasts all the advantages of merino garments: biodegradable, fire resistant, anti-bacterial, anti-microbial, machine washable, and UV protectant with an impressive SPF rating of 50+.

Users consistently give this shirt high ratings, proving that it’s the real deal when it comes to the performance they’ve come to expect from merino wool. This durable top features thumb holes for both women and men (thumb holes in men’s base layers are reportedly difficult to come by), and it’s the perfect shirt to grab when you aren’t sure exactly how warm or cool the day will be.

You can forge the trail ahead with confidence, knowing that—hot or cold, chilly or sweaty—this merino long sleeve base layer will do all the work to keep you comfortable. Just put it on and go!

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Minus33 Merino Wool Men’s Chocorua Midweight Crew

Minus33 Merino Wool Men's Chocorua Midweight Crew

Weight: 11.2 ounces

Dimensions: 10 x 7 x 3 inches

Specific features: The Minus33 Merino Wool Men’s Chocorua Midweight Crew features 100% 18.5 micron merino wool, flat lock seams, interlock knit construction, a UPF 50+ rating, a stretch cuff, and is entirely tagless for increased comfort.

Best use: This hardy garment is great for a fall outer layer or a winter base layer, and is available in extra large sizes for the big and tall members of your crew.

The Minus 33 Merino Wool Men’s Chocorua Crew is a high-performing mid-weight base layer that boasts a wealth of thoughtful features that prove this garment is the product of expert design. The interlock knit construction provides ultimate durability, and the flat lock seams have no potentially-irritating underside (unlike overlock seams) which guarantees all-day protection against chafing. The Chocorua Crew is also completely tagless, giving you even more peace of mind against chafing and irritation.

The stretch cuffs of this top ensure that the sleeves will stay in place as you layer (and remove) gloves and jackets, and the simple yet flattering look of the shirt make it perfect to wear alone on warmer days. As the Minus 33 folks point out, choosing a quality base layer is incredibly important before venturing outdoors in extreme temperatures. A good base layer won’t just make you feel comfortable, it can also provide you will valuable protection that might just save your life.

Related: The Minus33 Merino Wool Men’s Yukon Expedition Crew is a heavy duty mid layer shirt designed to take on the most extreme cold weather climates so you can retain heat and keep moving even on below-zero days.

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Icebreaker Oasis Crewe

Icebreaker Men's Oasis Long Sleeve Crewe Top

Weight: 12.2 ounces

Dimensions: –

Specific features: The Icebreaker Men’s Oasis Long Sleeve Crewe Top features 100% 200 g/m2 merino wool, a drop-tail hem for coverage from the elements, anti-chafe seams, and offset shoulder seams to prevent friction when carrying your pack.

Best use: This user favorite base layer is perfect for snow sports and cold weather hiking.

The Icebreaker Men’s Oasis Long Sleeve Crewe Top is a versatile, slim fit base layer that suits just about any outdoor activity imaginable. The offset shoulder seams won’t interfere with your pack to create chafing, and the drop-tail hem provides full coverage no matter how deep you bend or how high you reach. Flat lock stitching, a crew neck, and set in sleeves give this shirt a nearly seamless look and fit, and the 100% 200 g/m2 merino wool gives the wearer top-notch comfort, protection, ventilation, odor-resistance, and temperature control.

The Icebreaker Men’s Oasis Long Sleeve Crewe Top is game to go from the trail to the slopes to the pub while looking (and smelling) like it just came fresh from your closet. Users report that the high quality of this shirt’s merino are worth the extra dollars; many say this shirt is the softest, warmest, and best cut base layer they’ve ever encountered.

Related: The Icebreaker Men’s Everyday Long Sleeve Crewe Top is a lightweight, 100% merino wool base layer that features raglan sleeves, flat lock seam construction, and chafe-resistant forward side seams

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Mountain Hardwear Integral Pro

Mountain Hardwear Integral Pro

Weight: 7.1 ounces

Dimensions: –

Specific features: The Mountain Hardwear Integral Pro is made from a merino wool/polypropylene blend (Wick.Q Wool) and features flat lock seam construction, a 7.5-inch front zipper, and thumb loops to keep cuffs in place and hands warm.

Best use: This durable top will provide a toasty base layer for any winter activity, from cross-country skiing to hiking to beautifully icy mountaineering.

The Mountain Hardwear Integral Pro is a smart base layer made from a blend of merino wool and polypropylene for the ultimate in warmth, performance, comfort, and durability. The folks at Mountain Hardware call this signature fabric blend Wick.Q Wool, and they swear by its ability to wick moisture even more efficiently than wool, with the added benefit of drying faster than 100% merino garments. Thumb loops on this attractively cut base layer keep sleeves in place (and wrists warm), and the flat lock seam construction ensures that it can be trusted not to chafe as your skin’s first line of protection against the elements or additional layers.

The merino wool used in the Mountain Hardwear Integral Pro’s Wick.Q. Wool is sustainably sourced. Users report that this base layer is not quite as soft as others on the market, but that it performs consistently well in the field.

Related: The Mountain Hardwear Dryspun V-Neck Shirt is an expertly designed, moisture-wicking, lightweight, synthetic base layer perfect for warmer weather activities.

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Minus33 Men’s Ticonderoga Lightweight Crew

Minus33 Merino Wool Men's Ticonderoga Lightweight Crew

Weight: 7.4 ounces

Dimensions: 11 x 7 x 3 inches

Specific features: The Minus33 Men’s Ticonderoga Lightweight Crew is constructed of 100% 17.5 Micron merino wool (170 g/m2) and offers jersey knit construction, flat lock seams, stretch cuffs, and is machine washable and dryable.

Best use: This versatile base layer spans the seasons as a perfect choice for cold weather layering and a temperature-moderating top for summer play.

If you like backstories, this base layer is for you: the Minus33 Men’s Ticonderoga Lightweight Crew takes its product name from Fort Ticonderoga, which rests between New York’s Adirondack Mountains and the Green Mountains of Vermont. Traditionally, whoever controlled Fort Ticonderoga was the master of the surrounding region, so, by this logic, the folks at Minus33 guarantee that wearing the Ticonderoga Lightweight Crew will make you the master of the “comfort of your adventures,” no matter the region.

And this high quality base layer has the specs to back up the storytelling: the 100% 170 g/m2 merino wool elevates this shirt above its synthetic counterparts, and the jersey knit construction, flat lock seams, and stretch cuffs guarantee you optimal comfort and performance. This crew is machine washable and dryable, which will come in handy after those long-term adventures, when you’ve pushed the odor-repelling nature of merino to its absolute limit.

Related: The Minus33 Men’s Algonquin Short Sleeve Crew is a perfect summer base layer, offering optimal moisture-wicking capabilities and odor-resistance.

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Final Thoughts

Just like the key to a well-built house is a good foundation, the key to a well-built adventuring outfit is a good base layer. There are a wealth of base layers available in all types of fabrics and price points, but the experts agree: you can’t do much better than merino when it comes to covering all the important functions a base layer needs to cover in order to keep you comfortable, safe, and performing at your best.


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.