Merino wool base layers are becoming more and more popular, and for good reason. They’re soft, comfortable and keep you cozy warm in cold weather.
They efficiently wick away sweat and moisture. They’re also naturally odor-resistant, so you don’t have to worry about smelling stinky after a long trail day.
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Unlike other wools that are itchy, merino wool is soft and comfortable enough to be worn against bare skin. This makes it a perfect base layer.
Merino wool is all-natural and sustainable. It’s also a high-performance material, so it’s easy to see why it’s a top pick for outdoor enthusiasts.
What Exactly is a Base Layer?
Your base layer is the layer of clothes that’s right up against your skin. It’s the foundation of any clothing layering system for outdoor activity.
Your base layer is essentially your underwear or second skin when outdoors in cooler weather. This layer should be high quality and high performance.
Since your base layer is closest to your skin, there are certain qualities you should look for when shopping for a base layer to wear outdoors.
Material type, material weight and garment fit are all important factors to consider when shopping for a base layer that’s just right for you.
Is Merino Wool a Good Base Layer Fabric?
Merino wool is a top choice for outdoor clothing in any season. It’s a versatile material and it’s perfect for wearing against your skin as a base.
Although you might be thinking “Wool on my skin?! Sounds so uncomfortable!”, merino wool is different. It’s not scratchy at all.
Merino wool is woven from soft, ultrafine fibers for garments that feel like any other soft fabric. It’s very high performance, too.
Merino wool garments come in many different weights. They keep you warm, they wick moisture and they’re naturally odor-resistant.
How Should a Base Layer Fit Your Body?
One of the main purposes of a base layer is to wick sweat away from your body. This helps keep you warm and prevents bacteria growth.
So, in order to properly wick sweat, a base layer should fit snugly against your skin, but not so tight that it restricts movement.
The best way to think of a base layer is like underwear, but for your whole body. You want your base layer to fit snugly everywhere.
Base layers can be uncomfortable with other clothes if they’re too baggy or too tight. Comfortably snug is the goal.
What’s Different Between a Midweight and a Lightweight Base Layer?
The difference between lightweight and midweight base layers all comes down to temperature.
Lightweight base layers are best for moderate to cool temperatures while midweight materials are best for cold temperatures.
Meantime, heavyweight base layers are designed to keep you warm in freezing and below freezing temperatures.
Thinner base layers are best for the fall days that are transitioning from warm to cold, but you might want a midweight for overnight camping.
Base Layer Long-Sleeve Tops
Long sleeve base layer shirts are great for hiking and camping in cooler weather. Long sleeve base layers are comfortable even in moderate temps.
We’ve gathered the best long-sleeve merino wool base layer shirts here. You’ll find both midweight and lightweight options in this list.
The Smartwool Classic Thermal Merino Crew Baselayer from Backcountry is a midweight top that’s ideal for cold-weather conditions.
This shirt has a slim, snug fit. For comfort against skin, this top has flatlock seams and shoulder panels to ensure comfort all day long.
The flatlock seams minimize chafing and hot spots. The shoulder panels ensure comfort even if you’re wearing a pack.
* There are flatlock seams and shoulder panels for added comfort.
* It’s available in 7 color options, including black, vibrant blue, yellow and more.
* This shirt has a slim fit that’s snug and comfortable. This makes it easy to layer.
* As a midweight shirt, this shirt may be too warm on moderate days.
* This is one of the pricier options on the list, but the Smartwool brand is worth it.
* Not all colors are available in all sizes.
This midweight long-sleeve merino wool base shirt available at Minus33 comes in 12 different colors. Sizes range from XS to 3XL.
This shirt has a well-fitted princess-cut crew neck style for a snug fit without restricting movement. It’s great as a base layer or on its own.
Since it’s midweight, this shirt is ideal for temps of 0 to 30 degrees F while active, and 30 to 60 degrees F while inactive, per the manufacturer.
Customers rave about this shirt for its extreme softness and of course, the warmth. Reviewers love it for hiking, camping and for everyday wear.
* It comes in multiple colors and sizes.
* Some customers say this brand is softer against the skin than other brands.
* This shirt is a lot less expensive than the leading Smartwool brand.
* Some reviewers mentioned that this shirt runs a little long in the sleeves.
* This shirt has a standard 1 year warranty, but you get 2 years if you register it.
* Some reviewers mention that this shirt keeps them too warm.
The Moriah lightweight long-sleeve merino wool crew neck base layer is the lightweight version of the Ossipee.
Although this one only comes in 3 colors, it still has all the other great features that the Minus33 garments offer.
The merino wool is soft, the sleeves and shirt are long, it’s tagless, and it has flatlock seams for comfort.
Per the manufacturer, this shirt is temperature rated for 30 to 60 degrees F while active, and 60 degrees F and above while inactive.
* Customers love how efficient this shirt is at wicking away moisture.
* The added length in the bottom of the shirt is perfect for tucking into your pants.
* Flatlock seams and tagless design help prevent itch, hot spots and chafing.
* This shirt only comes in three different color options.
* Some reviewers complain that the sleeves run long.
* This shirt has a standard 1 year warranty, but you get 2 years if you register it.
Base Layer T-Shirts
Merino wool base layer t-shirts are a great option for both warm and cool weather. They can be worn alone or layered because they’re versatile.
If you’re on the hunt for the perfect merino wool base layer shirts with short sleeves, we’ve got you covered.
Not only does the Ortovox 185 Merino Rock’n’Wool top have excellent performance, it looks awesome, too.
This base layer t-shirt comes in two different color variations and sizes from XS to XL. It’s perfect as a base layer for hiking or camping.
This t-shirt is a midweight shirt, so it’s best for wearing in colder weather under a long-sleeve mid layer or jacket.
The Ortovox shirt is made with superfine 19-micron merino wool that feels soft, thermoregulates and wicks moisture away from the skin.
* This t-shirt comes in two super fun colors with asymmetrical designs.
* The Ortovox 185 shirt has a slim fit that’s not too snug, but not too loose either.
* This shirt is great for layering or wearing on its own.
* Reviews say this shirt felt itchy against skin but got softer over time.
* Color options are bright and bold, which might not be everyone’s cup of tea.
* This midweight shirt might be too warm to wear in moderate weather.
The Smartwool merino base layer shirt is great for layering in cold temps or wearing on it’s own on warmer days.
This is a lightweight merino wool shirt, so it can either help keep you warm or cool depending on how you choose to wear it.
This shirt comes in seven different colors and is available in sizes from XS to XL. It has a slim fit which makes it perfect for layering.
This shirt has flatlock seams to prevent chafing and shoulder panels to keep seams off of your shoulders for comfort with a daypack.
* This shirt is versatile and it will quickly become a favorite in all seasons.
* The slim fit isn’t too tight, but it’s not too baggy either.
* This t-shirt is available in a variety of colors and sizes.
* Customers note that there is little stretch to this shirt.
* The XL size seems to run smaller than typical XL shirts.
* Reviewers mention that the fabric can pill quickly.
Last but not least, this merino wool t-shirt from Merino.tech is a versatile pick and it’s budget priced, too.
This shirt comes in a very wide range of colors and sizes from XS to 2XL. It’s also available in different necklines.
Be sure to double check your size if you plan to wear it as a base layer. This shirt has a less snug fit than other base layer t-shirts.
The lightweight merino wool is great for moderate temps or wearing as a base layer on cooler days and nights.
* Many different colors and sizes make this shirt a great pick for anyone.
* A free pair of merino wool socks comes with this t-shirt.
* These shirts are 100% merino wool and perform as expected.
* These shirts seem to have a looser fit, which isn’t ideal for a base layer.
* These shirts only have a 60-day warranty window.
* This shirt style lacks the features that the other shirts in this list have.
Base Layer Bottoms
Your base layer bottoms are your protection against the elements and also the foundation that wicks moisture away from your legs.
Base layer bottoms should be soft, comfortable and give you full range of movement. We’ve included our top picks here that cover all the bases.
These midweight merino wool bottoms are a great base layer for both hiking and camping. They can even be worn alone on days with moderate temps.
The Franconia midweight bottoms fit like leggings. They’re recommended from 0 to 30 degrees F while active, and 30 to 60 degrees F while inactive.
Since they fit like leggings, they’re perfect for layering. They feel soft against the skin and wick moisture away quickly.
These bottoms come in sizes from XL to 3XL and are available in eight colors.
* A wide range of sizes and colors is available.
* The slim fit isn’t too snug, but it’s not too loose either.
* Flatlock seams prevent chafing and a gusseted crotch prevents friction stress.
* There are no pockets on these bottoms.
* The high-rise waistband doesn’t come high enough for some customers.
* One reviewer complained about pilling in the crotch/thigh area.
These Merino.tech merino wool base layer leggings come in a wide variety of colors and designs. They also come in both lightweight and midweight.
These are more budget-friendly merino wool base layer pants so they lack some of the features of the bigger brands. However, they are 100% merino wool.
The fit of these bottoms is snug, but not too tight. They’re great for layering if you get the right size.
If you’re considering trying out merino wool but don’t want to splurge on the name brands, Merino.tech is a great entry into the world of merino wool.
* These merino wool base layer bottoms are great if you’re on a budget.
* They come in a wide variety of colors and designs.
* The company sends out a free pair of merino wool socks with every order.
* These garments seem to lack the quality you’d find in other brands.
* Some reviewers complain about strange sizing.
* These bottoms may wear out near the seams.
The Smartwool Classic Thermal Merino Base Layer Bottoms are a fantastically warm midweight bottom option.
These bottoms are available in eight colors and sizes from XS to XL. With a snug fit, they’re perfect for layering.
The Smartwool merino bottoms have flatlock seams to prevent chafing and a curved back seam for a great fit.
These bottoms are midweight, but they’re not too bulky, so they’re comfortable enough to wear under your primary layer.
* Flatlock seams prevent chafing.
* A curved back seam prevents sagging in rear.
* Midweight fabric provides plenty of warmth.
* Smartwool is one of the more expensive brands.
* There are no pockets if you want to wear them on their own.
* Some say these bottoms are a bit itchy.