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?

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. 

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 in base layer thermals with secrets

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.
  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 snow pants, but waterproof is an absolute must-have feature. 
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 childrens 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.

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 childrens 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.

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).

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

Iksplor Kids Merino Base Layers

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.

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 so much, that we wrote a separate article just about their products, so make sure to check it out here.

Chasing Windmills Kids Merino 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

  • They 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 $74 per top and bottom set (an amazing deal for merino wool), and come in sizes 3 months to age 10.

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 childrens 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.

The Best Synthetic Base Layers for Kids

LL Bean Wicked Warm Expedition Weight Long Underwear

This is the softest kids base layer that I’ve ever found, 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).

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. 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.

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 thermals 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!

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 base layer for your kids, this is a great option.  This 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 base layer 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.  

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

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