Ultimate Guide: Best Thermal Underwear for Women (2024)

written by local expert Jane Elmets

Jane always knew she wasn't destined for a desk job... She has travelled all over the world and is passionate about noodles, sloths and her hiking boots! When she isn't busy adventuring around the world, you can find her reviewing travel gear and dishing out travel tips to all the places she's visited.

Looking for the best thermal underwear for women? In this article, I’m going to walk you through my personal top picks! You see, as a cold weather essential, thermal underwear for women is abundant. But how do you know which pair is best for you?

With so many pairs to choose from and a wide range of  materials, it’s hard to know what’s best for you. That’s why we put together this ultimate guide to best thermal underwear for women so you can stay toasty and comfortable, no matter how cold it is outside.

Our Picks for Best Thermal Underwear for Women 2024

Women’s Thermal Underwear: Comparison Table

ThermalsPriceMaterialWeightSet or Separates?Reviews
Minus33 Merino Wool Midweight$$$100% Merino WoolMidweightSeparatesView on Amazon
Icebreaker Merino Women's Everyday Thermal$$$100% Merino WoolLightweightSeparatesView on Amazon
MERIWOOL Midweight Baselayer$$100% Merino WoolMidweightSeparatesView on Amazon
ColdPruf Women's Quest Performance Base Layer$$85% Polyester | 15% SpandexLightweightSeparatesView on Amazon
Under Armour ColdGear Compression Shirt$$$100% PolyesterMidweightTopView on Amazon
Paradise Silk Thermal Long Johns Set$$100% Mulberry Silk KnitLightweightSetView on Amazon
Terramar Thermasilk Scoop-Neck Top$$100% SilkUltralightTopView on Amazon
Duofold Mid Weight Wicking Thermal$60% Cotton | 40% PolyesterMidweightSeparatesView on Amazon
Thermajane Ultra Soft Thermal Underwear$92% Polyester | 8% SpandexMidweightSetView on Amazon
MeetHoo Fleece Lined Thermal Underwear$95% Modal | 5% SpandexHeavyweightSetView on Amazon

What is Thermal Underwear?

Thermal underwear sometimes referred to as long underwear or long johns, is a base layer that you wear under your outer layers.

Thermals essentially trap your body heat (due to the tight fit) instead of letting it escape. During colder months, this is the first thing you put on. Then you layer everything else on top of it. This is the key to staying warm, especially on those bone-chillingly cold days or during winter activities like snow shoeing, skiing, or winter camping.

Made of different warm materials, long underwear is a saving grace in harsh winter winds and freezing temperatures.

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Why You Need Thermals

You need thermals to stay warm! Besides being super comfortable, this is the ultimate key to keeping yourself toasty when the cold outside is extra daunting.

Thermals are awesome because you get to layer everything else on top of it, and can shed those layers as it warms up throughout the day.

When participating in winter activities, thermals are especially important. Besides trapping your body heat, they also wick the sweat and moisture off of your body instead of absorbing it. This keeps you warmer than you would be just wearing a cotton long-sleeve under your coat.

I can’t recommend having a dependable base layer enough. They’ll come in handy more than you know, whether you’re braving the arctic tundra for an expedition or just going to grab a coffee in the snow.

What to Look for in Thermal Underwear

Choosing the right thermal underwear is super important, as they’re often quite pricey. You wouldn’t want to spend a lot of money on some thermals, only to find that they weren’t exactly what you need or want.

Here are four things to look for when deciding between different pairs.


The first thing to think about when it comes to thermals is the material.

With so many different options, it can get a little overwhelming, so here are the main fabrics you’ll run into, as well as the benefits (and possible downsides) of each.

Merino Wool

Merino wool is a top pick for long underwear, especially for activewear or taking on long trips.

Besides being super warm, this material effectively wicks away moisture and masks odor. This means you don’t have to worry about it getting smelly after a few days of hiking or adventuring in it! Total win in our books.

Merino wool is also pretty versatile and won’t be bulky under your other layers, making it a great choice. The only downside is it tends to be more expensive than other materials. Merino wool is the holy grail for thermals and other outdoor items. Check out our Ibex Merino Wool Clothing review as well as our Unbound Merino review for specific Merino Wool brands.


Okay ladies, they say that diamonds are a girl’s best friend, but have you met silk thermal underwear?

Silk thermals feel super smooth against your skin. They are also super lightweight, making them great for packing or days that aren’t as frigid. Silk wicks away moisture, but does require more frequent washing than merino wool.

Polyester Blends

Another common material for long johns is a polyester blend.

Mixing polyester with other fabrics like merino wool or synthetics make it a less expensive option while still properly locking in heat. It may not wick moisture as well, but it will keep you cozy, that’s for sure.


Finally, you’ve got your synthetic fabrics like spandex, nylon, and lycra.

Thermal underwear made of synthetics will be stretchy and more like typical leggings, which is awesome if you aren’t looking to spend a lot but want something that will keep moisture away from your body.

The downside to synthetics is that they lock in odors and aren’t as warm as other fabrics. That said, you’ll often find thermal underwear made from synthetics and lined with another material like fleece to make up for that!

If you’re wearing a base layer for heavy physical activity, it’s best to avoid cotton. Cotton will absorb moisture instead of wick it away, which will result in you being colder than you would be without the long johns in the first place. It may be the least expensive option but it completely defeats the purpose of thermal underwear and will leave you wet and smelly the second you start sweating.


Besides the type of fabric, you need to decide how heavy you want your thermal to be.

If you’re looking for everyday long underwear, you can probably opt for something lightweight and thin that you can slip on under your jeans or long-sleeve shirt. If you plan on doing more cold weather activities, you’re going to want something heavy to keep you warm in extreme cold.

Here are the main weights you’ll run into on your hunt for the perfect pair of thermals.

  • Ultralight – This is good for mild cold, and for daily wear when it starts getting chilly out.
  • Lightweight – A step up from ultralight, these thermals will be a little heavier without feeling bulky. You can wear them for daily use, but also for physical activity like skiing, winter jogging or even exploring a new city that has a bit of a chill to it. As long as you get that blood pumping, lightweight thermal underwear should suit you just fine.
  • Midweight – If you tend to get cold easily or are experiencing harsher conditions, you’ll want a pair of midweight long underwear. I personally go for this weight because I find them to be the most versatile. They keep me warmest, without overheating. Midweight thermals are good for skiing on colder days, snowshoeing, or going sledding!
  • Heavyweight – These thermals are for extreme cold. If you’re big into winter camping or backpacking, you’ll definitely want a pair of heavyweight thermal underwear to keep you warm when spending time outside in below freezing temperatures.
Girl leading man by his hand in snow


You can find thermals in a couple of different styles these days.

Typically, you can find a two-piece set that comes with a long-sleeve top and tight-fitting bottoms. That said, sometimes you’ll find tops and bottoms sold separately, so be conscious of that when shopping around.

You may also come across a full one-piece thermal suit. While pretty rare, a full suit is super useful for more extreme cold when you want to have continuous thermal protection instead of a gap between top and bottom.

Some long underwear come in unique fits like extra long (for all you tall gals), petite, or plus size to make sure that you have a pair that really fits you and your body type.

Whatever style you choose, make sure that you pick form-fitting, stretchy thermals. You can look for the term “four-way stretch” which indicates that the thermals are indeed as stretchy as you want them to be. These will be the most comfortable, provide you with the widest range of mobility, and keep you warmest.


Besides all of the basics, some thermal underwear will come with added features that are worth looking out for.

You may find some thermals that have thumb holes in the sleeves (great for skiing or backpacking), small pockets or compartments on the side or in the waistband for your phone or earbuds, high neck, v-neck, hoods, or UV protection!

One of my favorite features in heavyweight thermals is a fleece lining. This makes them unbelievably cozy! They aren’t the best for high amounts of activity because fleece absorbs sweat, but for the coldest days out and about, fleece-lined thermals are my go to.

Best Thermal Underwear for Women 2024

Here’s a roundup of some of the best thermal underwear for women out there. I’ve included a variety of material and styles, so hopefully you’ll find a base layer that’s best for you.

Minus33 Merino Wool Midweight

Material: 100% merino wool
Weight: Midweight
Available As: Separates
What We Love: Warm | Ideal for three-season use | 5 colors | Sizes up to 3XL

To kick off our list, we’ve gotta start with one of the best merino wool options out there. Minus33 is true to their name and creates thermals for those days that it’s below freezing.

Their 100% merino wool midweight thermal underwear is perfect for women who need that extra warmth, whether you’re running errands around town or hitting the slopes for a day of winter fun.

We love these because while they’re midweight, they’re also good for three-season use, making them the perfect outdoor companion. Plus, they only weight 8oz, so you can stash them in your bag without worrying about adding extra weight!

The one downside is these long johns are pretty expensive (as merino wool tends to be), and the tops and bottoms are sold separately. However, they come in 5 different colors and in sizes XS to 3XL!

Icebreaker Merino Women’s Everyday Thermal

Material: 100% merino wool
Weight: Lightweight
Available As: Separates
What We Love: Warm | Slim fit | Ideal for active & everyday wear

Here’s another awesome choice if you’re looking for thermals made from merino wool. Icebreaker is a reputable brand that makes quality base layers.

We love this thermal top because it’s perfect for everyday wear when it starts to get cold out. It’s slim-fitting so it will hug you for extra warmth. Plus, it has all the benefits of merino wool like odor resistance and moisture wicking.

This long john isn’t too heavy and is quite breathable, making it perfect for athletic wear or days when you’re on the fence about wearing a base layer at all. This is a go-to top for a lot of users because it’s not bulky at all, making it useful to wear in chilly offices or on cold commutes!

Unfortunately, these thermals aren’t sold as a set, so you’ll need to purchase the bottoms separately, but if you’re looking for a dependable, warm, and functional thermal top, this is a great option.

MERIWOOL Midweight Baselayer

Material: 100% merino wool
Weight: Midweight
Available As: Separates
What We Love: Warm | Super comfortable | Quick dry | UV protection

Want ultra comfortable long underwear? MERIWOOL makes some awesome thermal underwear for women with added benefits that make them practical for both everyday and active use.

The feature we love about these thermals is that they’re made from superfine, all-natural merino wool which has a softer feel than a typical wool layer. Perfect for those who may find wool scratchy or irritating.

They also have a loop for hang drying your layer, which is useful after a long day of hiking or even when you take them out of the wash. They’re quick dry so they’ll be ready to be worn again in no time. We love that these thermals offer UV protection and aren’t see-through at all. This means that you can wear them on their own and be protected from harmful rays!

Wear them under your jeans or as a base layer on a cold weather adventure — they’re sure to keep you warm!

The top and bottom are sold separately, but they’re a reasonable price for being 100% merino wool. Plus, these long johns come in three different colors.

ColdPruf Women’s Quest Performance Base Layer

Material: 85% polyester | 15% spandex
Weight: Lightweight
Available As: Separates
What We Love: Thumb holes | Super stretchy |Flat seams

Okay, to be honest, the most annoying thing about layering with long underwear is the sleeve of your base layer scrunching up when throwing on another long-sleeve shirt. But this Quest Performance base layer has (drum roll please) thumb holes! 

This is one of my favorite features in thermal underwear and will come in handy time and time again. Plus, it’ll keep your hands extra warm if you don’t have a pair of gloves.

Besides the amazing thumb holes, this top is made from 85% polyester and 15% spandex, making it ultra stretchy, super comfortable, and versatile.

The flat seams are there so you won’t be poked by the sewing as you may in other form-fitting tops. There’s even a drop tail to make sure that the shirt stays in place while running around.

Just watch out, the sleeves may fit a little tighter than other thermal tops.

Under Armour ColdGear Compression Shirt

Material: 100% polyester
Weight: Midweight
Available As: Top
What We Love: Perfect for active wear | Short turtleneck | Breathable but warm

Under Armour is a renowned athletic clothing brand and this base layer is no exception. This is an awesome activewear thermal top, perfect for cold weather sports and adventuring.

Some added features that make this base layer a cut above the rest: First, there’s a high collar (or short turtleneck). This is great for windy days or cold weather exercise because who wants to wear a scarf on a run? With this top, the heat will be trapped in from the neck down.

It’s also made from brushback knit fabric which is specially designed to keep you warm without overheating. When you start to sweat, the material also wicks moisture and dries quickly to keep you feeling comfortable.

If you want a piece of thermal underwear for active moments in cold weather, this is the option for you.

P.S., It’s advised to size up!

Paradise Silk Thermal Long Johns Set

Material: 100% mulberry silk knit
Weight: Lightweight
Available As: Set
What We Love: Super lightweight | Luxurious feel | 6 colors

Ooh baby, there’s nothing quite like the feeling of 100% mulberry silk knit against your skin on a cold day! This thermal set is true to its name, and really is paradise in a pair of long johns.

Silk is an awesome material for long underwear because it’s super lightweight, wicks moisture, and is breathable as well. These are great to wear around the house or under clothes when you’re feeling a little chilly.

These long johns are perfect if you’re on the hunt for an ultralight base layer that will fit snugly in your luggage without taking up room. They come in six beautiful colors as well.

Just beware that the material may shrink a little when washed. Besides that, this thermal set is truly heavenly.

Terramar Thermasilk Scoop-Neck Top

Material: 100% silky
Weight: Ultra lightweight
Available As: Top
What We Love: Super breathable | Luxurious feel | Perfect for layering

Another silk base layer, Terramar made this Thermasilk scoop-neck top to keep heat in and moisture out.

This thermal top is ultra-lightweight and is super breathable, making it perfect for daily or active wear. While it’s super lightweight, it’s also super strong, making it durable and long-lasting.

Only weighing 2 and half ounces, this is the perfect base for layering because there won’t be any added bulk.

Just be aware that this top is rather sheer so it’s best to be worn under something else or have a tank top underneath.

Duofold Mid Weight Wicking Thermal

Material: 60% cotton | 40% polyester
Weight: Midweight
Available As: Separates
What We Love: Double layered for warmth | Great for everyday use | No tags

While cotton is generally a no when it comes to base layers, this cotton-polyester blend makes this thermal a perfect everyday shirt.

It’s double layered to keep you extra cozy, and is thick enough to wear on its own without worrying about it being see-through. Because of the double layer, this long underwear is classified as midweight. This makes it a good choice if you’re looking for something a little thicker than the ones we’ve mentioned just above.

The polyester gives it a certain degree of moisture control, but it’s not the best for activewear. That said, this is a great thermal top for keeping out the cold, either as a base layer or on its own.

This long underwear is super comfy with no tags and flatlock seams, so you’re sure to be itch-free no matter when and where you wear this thermal shirt. For a full set, you can buy the bottoms separately.

Thermajane Ultra Soft Thermal Underwear

Material: 92% polyester | 8% spandex
Weight: Midweight
Available As: Set
What We Love: Stretchy | Material woven with argan oil | Great for activewear

Durable, stretchy, comfy, and extra soft, this is an awesome base layer for any type of winter weather or activity.

The polyester-spandex blend is a match made in heaven — the polyester creates durability while the spandex offers a good amount of stretch. The four-way stretchable design gives you a full range of motion, making it ideal for skiing, running, snow shoeing or just wearing around the house.

This shirt is super breathable and wicks moisture away instead of absorbing it, controlling odors and keeping you comfortable throughout the day.

The best part about the fabric of this material is that it was woven with argan oil. If you’re like me, you use argan oil to keep your hair super smooth, and it has the same effect on the fibers of this shirt. Seriously, this is one of the most comfortable base layers out there.

Plus, 8 different color choices… what’s not to love?

At a super reasonable price, wearers boast that there’s no difference between this top and the super expensive thermals!

MeetHoo Fleece Lined Thermal Underwear

Material: 92% polyester | 8% spandex
Weight: Medium / Heavyweight
Available As: Set
What We Love: Athletic design | Fleece lining | Ultra comfy

I mentioned my great love for fleece-lined thermals, and here’s a set that doesn’t disappoint in that department.

Perfect for the coldest days, this fleece thermal underwear set is so cozy and comfortable, you’ll stay warm no matter what. It’s a heavier set, made for staying toasty in freezing temperatures, but has a slim athletic design so you can still layer over it with no problem.

Besides keeping you warm, this long underwear set will also wick moisture, like all good thermals should. And it is breathable to ensure you don’t overheat if you wear it while exercising.

The only thing to note is that the set can run small, so be sure to consult the sizing chart before purchasing.

Caring for Your Thermals

Once you find the perfect thermal underwear, you’re going to want to be sure to take proper care of it so that it maintains its shape and lasts you for years to come.

The key is to wash your long johns as little as possible, which is reasonable considering most thermals have odor-resistant fabrics and moisture-wicking properties. Washing your thermals infrequently will help maintain these qualities!

Thermals can generally be machine washed in cold or cool water and then hung or laid flat to dry. Avoid washing them in hot water because this will cause shrinkage, no matter the material! Also avoid fabric softeners, bleach and other harsh chemicals. Be sure to consult the individual washing instructions of your particular long underwear to make sure you’re treating them right.

keeping warm in winter

Hopefully this guide to the best thermal underwear for women has showed you the importance of having a trusty base layer and led you to your new cold weather companion.

Stay warm, cozy and comfortable during any cold weather adventure with this awesome article of clothing!

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Ultimate Guide to Buying Thermal Underwear | Looking for a base layer for cold weather wear? Check out this ultimate guide to buying the perfect thermal underwear for you!
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