Best Thermal Underwear for Women (Winter 2020)

Best Thermal Underwear for Women

With winter fast approaching, I thought I’d do a 3-part series for the best thermal clothing.  This is part 1 – the best thermal underwear for women.  Here are links to the other parts, best thermal underwear for men and best thermal socks.

When the temperatures start to drop and you need to add extra layers, thermal wear should be at the top of your list.  It’s warm, lightweight, comfortable, and over recent years has become a versatile piece of clothing. The best thermal underwear for women can be worn while sleeping, out skiing on the slopes, or while taking the kids to a soccer game. There’s thermal clothing made for just about every activity that you can think of these days.

In the past, the best long underwear for women was thick, bulky, heavy, and frankly, just uncomfortable to wear. It looked awkward at best.  Now there are a number of top brands that focus specifically on thermal underwear for women.  You can find different thicknesses, different materials, and even different styles. Many of the women’s thermal underwear sets are made to be seen as part of your outfit now. They aren’t like the old long johns your mother wore 30 years ago.

Throughout our search, we focused our Best Thermal Underwear for Women list on warmth, comfort, versatility, and affordability.  Some of the higher quality pieces aren’t cheap, but keep in mind that cheap, thin, cold thermal clothing won’t do you any good.  Our stance is that you are better off getting one great set of the best thermal clothing versus buying several sets that won’t do you any good in keeping you warm.  That being said, here’s the list of reviews!

Merino wool thermals by Minus33 come in three different weights: lightweight, midweight, and expedition.  Their lightweight line is actually designed to be worn year round and can even be worn as a solo piece.  The soft Merino wool material does a great job at regulating temperature and is also naturally moisture wicking.  It’s odor resistant and machine washable and dryable.  MIdweight has a little more insulation, but still has all the same features that the lightweight wool does.  And for those thrill seekers or those that love the extreme cold, the Expedition line is for you. 

We think Minus33 makes the best women’s thermal tops of the group!

Minus33 Merino Wool Women's Thermal Underwear


  • Keep warm –  merino wool is the best material for thermal wear.
  • Versatile – Can be worn as a base layer or can be worn alone.
  • Wide range – Minus33’s tiered approach covers you whether you’re looking for something lightweight or going to Antarctica!


  • Price point – Due to the fact that Minus33 utilizes merino wool in most of their thermal products, the price point is higher. However, I’d rather have one pair of good merino wool thermals than 3 pairs of lousy ones any day.

Cuddl Duds thermal wear items have become pretty popular in recent years.  Their stuff is soft, stretchy, and lightweight.  Cuddl Duds are specifically meant to be layered.  In fact, it appears to be their motto, “Live in Layers”.  Most of their products appear to be a thinner, Spandex material. 

In our opinion, Cuddle Duds offer the best base layer for everyday use, including the best women’s long underwear bottoms that fit under jeans.  

Cuddl Duds Software Comfortware


  • Thin and lightweight – Product uses Spandex-type materials so they are much thinner than wool and fit well under jeans, etc.
  • Good for layering – traps body heat
  • Ultra-Comfortable – Cuddl Duds are cozy & comfortable, even for lounging around the house
  • Affordable – Best price-conscience thermal option


  • Extreme cold – Not suitable for extreme cold conditions unless also layered with a wool product
  • Not Versatile – As a layered product, many pieces look more like long underwear and are not appropriate to wear on their own.


SmartWool is a higher-end brand with great thermal products for an active woman.  Their products also use merino wool and are great cold weather clothing.  They are definitely more than just “long johns”.  Their pieces are meant to be stand on their own, and SmartWool stands behind their product.  They even offer a guarantee that you’ll be happy with your purchase or they’ll take it back up to two years after the purchase.   

For this reason, we like SmartWood as the best base layer for extreme cold temperatures.

SmartWool Womens Underwear


  • Great fit – Numerous reviews of SmartWool say that their clothing fits great
  • Merino wool thermals – warm, moisture-wicking, and sustainable for the environment
  • Looks great – Their clothing is meant to look good, fit good, and feel good. This is not a “cheap” item. 


  • Price-point – Because they use merino wool, pricing is less affordable. Many actual customers say that it’s worth it to get the good fit and warmth of the wool.



Ekouaer fleece-lined set of thermal underwear doubles as either thermal pajamas or a base layer for under your clothes at work or during outdoor activities.  The legging-style pants and thermal top are of a medium weight and fit nicely.  It’s a 2-piece set and provides a super comfortable curvy fit. Don’t they just look comfy???

These are the best women’s thermal underwear sets for their price-point!  

Ekouaer Thermal Underwear Fleece-Line Long John Sets


  • Versatile – wear as warm PJ’s or as a base layer under clothes
  • Fleece-lined – warm, but not to warm
  • Low Cost – lowest price option on the top 5 list!


  • Extreme cold – not warm enough for very low temps


Paradise Silk makes an ultra-light weight womens silk long underwear.  Their thermal long johns set featured here is made of 100% mulberry silk knit and comes in numerous colors.  This super soft fabric feels great against the skin and keeps your body heat in, but wicks the moisture away.  They are great for skiing, hiking, and hunting, or just lounging around the house.  

We think these silk thermal underwear actually make the most comfortable thermal pajamas! 

Paradise Silk Long Johns


  • Very thin & light weight
  • Silk knit – soft and “silky” smooth
  • Great for layering


  • Not as warm as merino wool, but is a great extra layer

Thermal Underwear for Women:  Materials

 There are numerous materials used in thermal underwear for women.  I’m sure we won’t catch them all, but we’ll cover the most common.


Merino Wool

Merino Wool is one of the warmest.  It’s naturally moisture-wicking and breathable.  It is super soft, flexible, provides UV protection, and even insulates when wet.  Wool absorbs up to 30% of its weight in moisture before feeling wet!  Merino wool thermals are odor resistant (nice!) and anti-microbial.  In fact, it’s a renewable, recyclable, and biodegradable material, meaning it leaves a low environmental footprint.  Its only downside is that it’s a bit pricey, but worth it if you need something ultra-warm.  Another plus for merino wool thermals is that many of the pieces made of this material are actual clothing and not just a base later.  This means you’re getting double the benefit out of this piece!  We believe merino wool makes the best thermal underwear for women, especially if you’re main goal is warmth.



Fleece-lined thermal underwear for women is not quite as warm as merino wool, but it’s a great, lower-cost compromise.  It’s heavier than silk and spandex and can be very comfortable over the skin. 


Silk is a smooth, thin, and light weight fabric used for women’s thermal clothing.  This ultra-thin material is great as a base-layer under other clothing or to be worn as lounge wear.  It’s moisture wicking, but keeps your body heat in.


Similar to silk, spandex is thin and light weight, but that’s where the similarities end.  Spandex is a tighter fit and has become popular in leggings in recent years.  It’s also a good fit as a base-layer as it fits well under other clothing. 


Best Thermal Wear Brand for Women

The best thermal wear brand for women depends on your needs of course.  With ladies thermals being made out of so many different materials, each having their own customer-base, you can’t pick without first defining your needs.  Our favorite for each material is as follows:

Merino WoolMinus33

SpandexCuddl Duds

SilkParadise Silk


Layering Thermal Clothing

Everyone knows about layering their winter clothing, but do you know why?  It traps air between layers, providing a thermal insulation.  It also allows for changing how warm or cool your clothing is without changing your clothing.  You can just add, or shed, layers as conditions change.  Let’s look at the layers.

Layering Thermal Clothing

Base Layer (also called the inner layer)

The base layer of your thermal clothing is basically moisture management.  It’s important to use a material that is moisture wicking.  You want it to keep your perspiration away from your skin and keep you dry during cold conditions.  Good materials for this layer include nylon, polyester, merino wool, and silk.  Here’s a great article from REI on How to Choose Base Layers.

Mid Layer

The mid layer, or middle layer, of your thermal clothing is there to provide insulation to keep in warmth.  This layer is often both thicker and more loose-fitting than the base layer.  This leaves a small gap for insulating air between layers.  Popular materials for the mid layer are wool, fleece, and down.

Shell Layer (also called the outer layer)

The job of the outer layer is too keep both the wind and rain out!  They are often water-proof, or at least water resistant, and breathable.  They range from lightweight wind breakers, to raincoats, to heavier winter jackets.

Best Womens Thermal Onesie

Recently I came across what looks like the most comfortable thing ever, the women’s thermal onesie.  They remind me of my childhood pajamas except they aren’t footies :).  No, these don’t have the built in socks, and they don’t zip all the way from your neck to your toes.  They are a super-comfy thermal pajama that buttons from the waste to the neck in the front like you see here in the picture.  This particular option, our favorite by the way, is made of 95% cotton and 5% spandex.  It’s a mid-weight, soft, and warm.  It can also be used as an inexpensive base layer in a pinch, but because it’s made of cotton, it’s not the warmest, nor the best material for wicking moisture.  We feel these are a great thermal pajama, but are not a good long term solution for under clothing.  This Hotouch Womens Thermal Onesie is available at Amazon and comes in 7 colors!

womens thermal onesie

Best Thermal Underwear for Women Travelers 

If you’re a traveler, the best thermal clothing for you while on the road is something made of merino wool.  I know this might be starting to sound like a broken record, but it’s suited for many needs.  Specifically beneficial for travel, merino wool thermals can be worn several times before they are washed.  The material is also lightweight, super warm, and wicks moisture.  Unfortunately, it isn’t the lowest cost option, but because the pieces are so effective at keeping you warm and can be recycled through several outfits, they are worth it. 

Our favorite women’s thermal underwear made of merino wool is: Minus33’s Ossipee Crew

Thanks for reading our post about the Best Thermal Underwear for Women.  See below for parts 2 and 3 in our series of best thermal clothing. 

Best Thermals for Men

Best Thermal Socks