The Best Kids Base Layers – The Secret to Staying Warm In Winter

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The cold temperatures of winter are just around the corner – are you ready for it?  

Perhaps the better question is, do you have everything your kids need to go out in the cold this winter?

SPOILER: Skip ahead to our favorite kids merino wool base layers and our favorite kids synthetic base layers, with low prices and discounts for you!!

While it’s easy to think that all kids need are good boots and a nice coat to play outside in the winter, there’s a whole lot more that goes into keeping kids warm in the winter than just that.  In fact, staying warm starts at the very bottom – with choosing the best kids base layer (and of course topping everything off with a waterproof coat or snowsuit, and kids snow pants. 

By now I’m sure that you’ve heard that the best way to dress for the outdoors is in layers.  Layering kids clothing helps them to regulate your temperature better without getting too hot or too cold. Kids layers are extra important since they’re rarely holding still and it’s easy for them to get hot and sweaty (and then quickly freeze after that).

Kids Wool Base Layers, Quick Picks:

Chasing Windmills: Hands down our favorite for kids and women. Their traditional merino wool long johns have reinforced knees and last forever, but we especially love their ribbed merino thermals which are the softest base layers we’ve ever had. Also check out their Mid Layers HERE.

Iksplor: Lightweight and soft, perfect for a comfy base layer to wear under just about anything. Great quality!

Reima Taitoa: Bamboo lined for super soft feel
Reima Kinsei: Basic and Affordable

Kids Synthetic Base Layers, Quick Picks:

Shred Dog: Thicker, super warm, brushed lining for softness
Reima Lani: Great for layering, good wicking
LL Bean Expedition: Very warm, stretchy, cool hood

Base Layer Discount Codes:
Ikslpor 20% off with code bringthekids
Reima 20% off with code BRINGKIDS20
Shred Dog 20% off with code BRINGTHEKIDS

Here’s a quick rundown of how to layer your kids clothes for winter adventures.

  1. Base Layers. Kids base layers are always what should be going on first, and it should be a high-quality base layer for kids that both insulates and wicks sweat away from the body. Synthetics and merino wool base layers for kids are our favorites for base layers and there several great kid options in both materials.

    Each of our kids has two sets of base layers — one that’s lighter weight and the other that’s a heavier weight for really cold days. Below, we are sharing some amazing options to help you choose the best base layers for kids. They wear them everywhere from skiing in winter to camping in the summer.
  2. Socks. We won’t wear anything besides wool on snowy days, and only one pair (doubling up always creates a mess). Wool socks are an absolute life-saver in winter, so make sure to have several different pairs since your kids might want to wear them daily. These socks have a lifetime guarantee!
  3. Mid-Layers. This is your insulating layer, but don’t go overboard here since putting too many clothes on will make your kids sweat.   My favorite mid-layer material for kids is fleece.
  4. Coats Getting your kids good outerwear is an investment that will pay off over and over again. We’ve handpicked the 15 best waterproof coats for kids here.  
  5. Snow Pants. You don’t need anything fancy when it comes to great snow pants, but waterproof is an absolute must-have feature. Read our review of the best kids snow pants! 
  6. Boots. Having cold feet will make kids feel miserable, so get them a good pair of winter snow boots.
family in winter in the snow

What are base layers?

A kids thermal base layer is the very bottom layer of clothing that kids wear.  When I was a kid, we just called them thermals or long underwear, and they were usually made of a horrible waffle weave cotton material.  Thankfully things have come a long way since then, and most children’s base layers are either made of wool or synthetic materials.

Cotton is a poor insulator and performs horrible if it gets wet (like from sweat), so absolutely avoid it waffle weave kids thermals that are made of cotton.

Even the best base layers are not meant to be worn individually, but rather as part of a bigger layering system. Kids baselayers work great as pajamas, and you should be able to wear your normal clothes on top of your base layers as well.

Many people ask how many layers should you wear in the winter to stay warm? We always recommend one base layer, one mid layer (our favorite is fleece), and one layer of outerwear.

While you‘re getting ready for winter, don’t forget to check out our other winter gear reviews for kids:
Best Kids Snowsuits
Best Waterproof Gloves and Mittens for Kids
Best Kids Base Layers
Best Snow Boots for Kids
Best Kids Face Masks
Best Ski Harnesses for Kids
Best Kids Ski Socks, Guide to Winter Clothes for Toddlers and Babies

Can you wear base layers under clothes?

Yes, in fact, base layers should be worn under clothes. In the winter my kids wear base layers under jeans, they wear base layers when they go running, and my daughter even wears base layers under dresses. Base layers are the perfect way to regulate your body heat.

Boys Base Layers vs Girls Base Layers

As is common with most types of underclothing for kids, boys baselayers and girls baselayers can be a little bit different (just like underwear). If you want your children’s thermal baselayers to be able to be passed down from boys to girls, make sure to get a boys base layer with a flat front.

Should you wear underwear under base layers or underwear under long johns? Obviously that’s a personal preference, but in our family, the answer is YES.

Merino Wool Base Layers

Merino wool has increased in popularity significantly over the past decade for some very good reasons.  Merino is one of the best materials for adventure lovers for a few reasons:

  • It helps regulate body temperature
  • It’s naturally antibacterial, so it helps to absorb odors (meaning you can wash it less)
  • It’s lightweight
  • It wicks very well
  • It’s super soft

We love merino wool so much that we wear it year-round (it’s a great cooling fabric), and include it in our travel capsule wardrobes for the kids.  Although most merino wool base layers for kids recommend that it be air-dried, I usually just dry ours on medium-low with the rest of the laundry and have never had any problems with shrinkage or durability. 

The main drawback of merino wool long underwear for kids is the cost, as it can be quite expensive (though our merino wool clothing seems to last forever, so I think it’s absolutely worth the cost). Many people consider merino the best base layer kids can wear.

Synthetic Base Layers 

There are several different types of synthetic materials for base layers.  The most common materials are polyester and polypropylene. Both dry quickly and do a good job of moving moisture away from the body.  Synthetic materials tend to hold on to odors, so it’s very common for synthetic base layers to start smelling bad after a while if not properly cared for (and it’s incredibly difficult to get the smell out).  Synthetic base layers come in all shapes, sizes, and textures, and are usually significantly cheaper than merino wool.

The Best Merino Wool Base Layers For Kids

Chasing Windmills Kids Merino Base Layers

Pros: Most durable with reinforced knees, lowest price Merino Wool base layers

These base layers are so amazing.  They are some of the softest merino we’ve ever had and it just keeps getting softer every time I wash it.  They are designed by parents of twins who felt inspired to connect children with nature through the clothing that they wear.

So far, they are our favorite toddler merino base layer (they also make gorgeous merino wool thermals for babies).

baby and girl talking

My daughter loves them so much that last week she wore them 4 days straight (as pajamas for bed, and layered under clothes during the day).  In the end, they didn’t smell at all (though I still told her it was time for new clothes).  

A few things that we love about Chasing Windmills merino base layers for kids

  • Their childrens base layer thermals fit well without being too tight.  They are a good fit on my 10-year-old but have some extra length so I can also have my 12-year-old wear the same pair without it being too tight.
  • They are easy to wear under clothing 
  • The knees are reinforced so that you don’t get holes
  • Cute patterns and colors.  
  • They grow with your child really well. Our youngest has worn a size 2, until he was starting to wear normal size 4 clothes. These are amazing toddler base layer clothing.
boy with sneaky look on face in thermals base layer

Chasing Windmills base layers start at $77 per set including both top and bottom and come in sizes 3 months to age 12.

Iksplor Kids Merino Base Layers (discount below!!)

For 20% off your Iksplor purchase use the code bringthekids at checkout.

Pros: Lightweight, super soft (perfect for sensitive skin)

Iksplor kids base layers are some of our all time favorite merino wool base layers for kids. The merino wool is incredibly soft and our child who has a sensitivity to textiles absolutely loves them (now that’s saying something) and he’ll happily tell you that this is the best merino base layer ever.

Thankfully, they are naturally odor absorbing, since my son wears them at least 3-4 days a week during the winter (read all about how this kid base layer is a great fit for kids who are sensitive about what they wear). He tells everyone he knows that these are the best thermals for kids when they ask him about his blue outfit.

Some of our favorite things about Ikslpor kids wool long underwear base layers for kids:

  • This kids wool base layer is lightweight which makes them perfect for layering all through the winter and even into the summer.
  • The childrens baselayers are generously sized. My son is between sizes and REALLY skinny. We ended up going a size down, and I know they’ll still fit him into next winter since the length is generous.
  • Iksplor is a small business that’s run by moms and their products are made in the USA!
  • All of their pieces are machine washable and dryable.

We love Iksplor merino wool base layer kids products so much, that we wrote a separate article just about their products, so make sure to check it out here. We wear these base layers for skiing, and also wear these base layers for winter adventures and snow hikes.

Reima Taitoa Merino Wool/Bamboo Blend Kids Base Layer

Pros: Super soft, warm, fun patterns

Use code BRINGKIDS20 for 20% off Reima

Reima really outdid themselves with this blended wool and bamboo base layer for kids. My daughter wears them almost every day, because they’re SO SOFT. The soft bamboo is next to kids’ skin to make it feel smoother and softer and to help absorb moisture.

The wool on the outside keeps children warm and controls their temperature, whether they’re hot and sweaty from playing or just sitting around in the cold. The Reima Taitoa is a great choice for kid’s base layers if you want them to feel really comfortable. They’re also great for kids who don’t enjoy the feel of merino wool on their skin since the bamboo layer is what comes into contact with the skin!

Reima Kinsei Merino Wool Kids Thermals

Pros: Stretchy, affordable

Use code BRINGKIDS20 for 20% off Reima

At our home, these wool thermals are on constant repeat. They’re made of stretchy merino wool, which makes them appear to grow as your children do!

These are ideal kids thermals for children who spend a lot of time outside, allowing them to keep their core temperature stable whether they’re hot and sweaty or chilly! These go up to a size 14, so they’re great thermals for teens!

Icebreaker Merino Wool Kids Base Layers

Our kids have been wearing Icebreaker base layers for the last 8 years, and it’s a company we have grown to trust and love.  Made in New Zealand and you can actually track the sheep that your clothing is made from with their baacode program (the kids LOVE this). 

Their children’s merino thermals have been around a long time, and our kids have gotten some serious mileage out of their merino wool kids clothing.

boy in merino wool

Icebreaker has an incredibly extensive line of merino wool products, and one thing that I really like is that you can buy different weights of merino clothing, depending on your needs.  For example, you might buy a 300 weight for extra cold days, a 200 for day-to-day winter layering, or a 100 weight for a t-shirt.  

Icebreaker base layers are sold as individual pieces, and retail prices start around $50 per piece. Since Icebreaker has been around for so long, you can often find discontinued pieces of their kids merino wool base layer online, which helps make buying merino wool for kids more affordable. This is one of the most affordable wool base layers for kids.

The Best Synthetic Base Layers for Kids

Shred Dog Foundation Base Layers: Best thicker base layers

Our new favorite base layer for kids is from Shred Dog, a company that specializes in high quality ski clothing for kids. Their kids Foundation base layers are hands down the softest base layers I’ve ever found for kids, with a smooth outer layer combined with a brushed lining making them super comfortable.

Remember at SHRED DOG, use the code BRINGTHEKIDS for 20% off any regular priced order

These base layers from Shred Dog are thicker than most of the other base layers for kids that we’ve tested here in this review. While we’re still waiting to test them in extreme winter conditions (Fall 2020 is our first time trying these children’s base layers), our initial impressions are great, and I am anticipating that they will be some of the warmest base layers for kids that we’ve found.

So far our kids have tested them on a cold desert camping trip that was freezing at night and hot during the day (75 degrees). My daughter wore her top the entire time. She kept telling me that she loved that she could have one top that kept her warm in the cold, but also wicked her sweat away in the heat when she unzipped the neck. I feel pretty confident that these will make great base layers for skiing since our kids are constantly alternating between hot and cold when they’re sweating down the ski hill and freezing on the chairlift. Check out our full review of Shred Dog ski clothing for kids (including outerwear).

While many of the base layers that we are featuring work best as a very bottom layer, the Shred Dog base layers are clothing that I can see my kids wearing both as base layers and as every day clothing. My daughter especially loved the base layer pants which basically feel like fleece lined leggings, so she can wear them to school in place of leggings, while still feel fashionable and warm all winter long. The base layer top has the same brushed interior, and with a 1/4 zip neckline, it’s also a great piece to wear for everyday play for kids. Prices for Shred Dog base layers for kids start at $30.

Shred Dog also makes an advanced seamless baselayer top, also with a 1/4 zip. The material on this is really stretchy and cozy, and I think it will end up being my daughters go-to top for super active days, like nordic skiing. As a mom, my favorite feature is that while it has a 1/4 zip for comfort and ventilation, there is a mesh gusset behind that to help her stay modest even when she’s sweating!

Reima Lani Best Kids Thermals, lightweight

reima lani

Use code BRINGKIDS20 for 20% off at Reima

The Reima Lani is a fantastic basic option if you’re searching for an excellent pair of kids thermals. These kids thermals are fantastic at wicking moisture away from the skin and keeping kids warm.

These are a lightweight thermal set that’s good for layering under other clothes, and they’re ideal beneath a decent children’s mid layer. This is a great pair of kids thermals for teens up to size 14.

LL Bean Wicked Warm Expedition Weight Long Underwear

This is a really cozy set of long underwear for kids, and the kids expedition weight base layer is excellent for really cold days.  The inside is lightly brushed and feels fantastic next to the skin.  One of my kids is incredibly picky about textures and fabric and he absolutely loves the feel of these. 

boy in thermals

While these are named expedition weight thermals, they’re really just slightly thicker than average but are some of our warmest base layers for kids.

The thing that really sets them apart is the construction.  For the top, you can buy a quarter zip-top, or you can get a hooded top with a balaclava (can be worn with or without the face shield). If your kids have to wear a face mask anyway, this LL Bean top is the perfect winter piece! Overall they are one of the best cold weather base layers for kids.

boy in balaclava winter

This is perfect on really cold days, or great for those days when the weather is constantly changing and you need to be prepared for anything and everything!  The top also features thumbholes to keep wrists warmer. LL Bean Expedition Weight Long Underwear starts at $25 per piece and are available in sizes 4-18. We

As a mom of both boys and a girl, I especially love that their bottoms are not gender specific, so that these boys base layers can also be worn as girls base layers. If you’re looking for the best base layer for cold weather, you need to consider these.

Stripes Gear Thermals for Kids

Stripes Gear is a Canadian company that makes base layer thermals for the entire family.  All of their kids long underwear base layers are made of polypropylene so they do a great job of wicking moisture away from the body.  True to their name, all of their sets come in fun stripes in all different colors.

boy in stripes thermals

Stripes thermal long underwear for kids are the way to go if you’re wanting to get several seasons worth of wear out of your base layers.  My 7-year-old and 10-year-old can easily wear the same pair, and my 12-year-old can also fit onto them (though they’re too short).

Just like the Chasing Windmills base layers, Stripes also have double knees to make sure that they last extra long without getting holes.  They are incredibly stretchy, and also super warm. Since these thermals are made of polypropylene, DO NOT dry them – they can melt! For a synthetic fabric this is one of the warmest base layers for kids.

Stripes thermals start at $20 per piece and are available in sizes 2-12 for kids.  

LL Bean Wicked Warm Midweight Long Underwear

If you’re looking for a good quality no-frills winter base layer for your kids, this is a great option.  This kids thermal base layer isn’t as soft or comfy as the LL Bean Expedition weight, though it still does a good job of insulating on a cold day.  Featuring thumbholes in the shirt, this base layer does an excellent job of keeping arms and wrists warm.

boy in ll bean thermals

This is a great ski base layer for kids if you’re going to be doing a lot of layering since it’s pretty lightweight.  LL Bean Midweight Long Underwear starts at $20 per piece and is available in sizes 4-18.  

Best Base Layers for Babies and Toddlers

Iksplor Baby Set

These are our favorite base layers for babies and toddlers. The Iskplor Baby Set comes in sizes 0-3 months, 3-6 months, 6-12 months, and 12-24 months. It does run large which is perfect for growing kids. They are still very fitted in the torso they are just made to be longer in the torso, legs, and arms to provide extra protection and warmth. They even have fold-over mittens on the sleeves. I get my baby and toddler their regular size and they fit for a really long time. They come in the cutest colors.

The best part about Iksplor’s Baby Set is that it is machine washable. Since they are antibacterial they don’t need to be washed very often. When I do want to wash them I get all of our Iksplor sets and wash them on cold and then hang them dry or dry on low.

For 20% off your Iksplor purchase use the code bringthekids at checkout.

Iksplor Adventure Zippy

Merino wool is perfect for babies and toddlers because merino wool keeps them warm and dry. The Iksplor Baby Adventure Zippy is so buttery soft and perfect for right next to their skin. 

The Iskplor Baby Adventure Zippy comes in sizes preemie baby, 0-3 months, 3-6 months, 6-12 months, and 12-24 months. It does run large which is perfect for layering with the Baby Iksplorer Set. I get my kids their regular size and they fit for a long time.

Double zipper on the Iksplor Adventure Baby Zippy

My babies always get so cold when I have to change them outside and the double zipper makes it so easy to change them. My baby wears her Iksplor Adventure Baby Zippy multiple times per week and we even use it as pajamas, especially when we go camping. 

I am always looking for good quality gear that I can use as long as possible. The Adventure Zippy is perfect for this. We can use it in the winter to keep our baby warm and is perfect for sun protection in the summer.

For 20% off your Iksplor purchase use the code bringthekids at checkout.

Iksplor Kid Set for Toddlers

The Iksplor kids set is made with 100% merino wool. The merino wool doesn’t cause any chafing or irritation in my kids. Choosing high-quality merino wool can make such a difference when going on adventures with kids.

If you’re looking for more ways to stay warm this winter in addition to buying the best base layer for kids, check out our buying guides on waterproof snow boots, the best kids coats, puffy coats for kids, and the best kids gloves and mittens and snow pants,

About Jessica Averett

Hi, I’m Jessica, a mom of 5 kids and married to my favorite adventure partner. I love to bike, ski, camp and hike. We've visited over 40 countries with our kids, but are equally happy on the road as we are exploring our home state of Utah.

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