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How to Choose Base Layers for Women

By Amber King ⋅ Senior Review Editor
Friday November 8, 2019
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A solid base layer top is one of the most important parts of your outdoor outfit. It's the layer that sits right next to your skin, underneath a mid-layer like a fleece, and further layered underneath a jacket or shell. It's biggest job is to keep moisture off your skin while providing comforts that have you wearing it from the ski hill to the chalet with ease. While many will wear these tops underneath layers in colder weather, they can also be worn as stand-alone pieces in warmer months. So what kind of base layer should you buy? In this article, we explore everything from budget to fabrics and fit. This guide will put you well on your way to finding your the best base layer top that'll have you lookin' fine while keeping you safe from cold weather.

Alison hangs out in Red Rock Canyon  Nevada. She stays warm and cozy in the highly versatile Arc'teryx Rho LT base layer - our favorite synthetic layer.
Alison hangs out in Red Rock Canyon, Nevada. She stays warm and cozy in the highly versatile Arc'teryx Rho LT base layer - our favorite synthetic layer.

Learn more about layering by checking out our Introduction to Layered Clothing Systems article that explores what a fantabulous layering system looks like.

Budget


How much should you spend on a good base layer? A higher price doesn't necessarily dictate a base layer, but a lot of the time, that trend is true. The base layers that perform the best are merino wool, which costs more than synthetic layers. Look at spending just over one hundred doll-hairs if you want the best of the best. More than that, you're probably overspending. You can also find great deals for less than one hundred, but probably miss out on some comforts and a fabric that thermoregulates well.

Fabric Types


Knowing your fabrics is probably the most important part of buying a good base layer. Make sure you do not buy a base layer made of cotton. Here we discuss four different fabrics that you will come across: cotton, synthetics, wool, and wool-synthetic blends. We outline the pros and cons of them all.

When buying a base layer top, check the tags to see what the fabric make-up is. If shopping online, be sure to click on the "specs" tab to see what the materials are constructed from. Avoid cotton or cotton blends at all costs if you plan on going into the backcountry. They will not keep you warm in cold or wet weather and can actually be dangerous to choose in these conditions.

Merino Wool


The outdoor industry has come a long way since the age of thick, heavy, and utterly itchy union suits that soldiers would wear on the front lines in the early 1900s. Thanks to a push for better technology, and Merino's "ultra-fine" fibers, wool has evolved. It's not itchy, too hot, or heavy, and it is one the best temperature regulating fabrics out there, making it great for all seasons. Not only that - but it doesn't develop a long-term stink! Perfect for those long trips where you simply can't wash up!

The Smartwool 250 is our favorite for ski touring and simply hanging out at the chalet after a cold day on the slopes. The merino wool offers great thermoregulation to keep you warm all day.
The Smartwool 250 is our favorite for ski touring and simply hanging out at the chalet after a cold day on the slopes. The merino wool offers great thermoregulation to keep you warm all day.

Pros
  • Fantastic temperature regulation
  • Natural fibers
  • Easy Care
  • The odor is not an issue
  • Warm when wet
  • Amazingly cozy on the skin

Cons
  • Less durable (holes easily appear)
  • Longer time to dry
  • Absorbs more water
  • Typically heavier in weight
  • Typically more expensive than synthetics
  • Some folks are allergic to this natural fiber

Synthetics


Garments constructed with synthetic fabrics are often either 100% polyester or a blend of synthetic materials. While these garments are typically less expensive and quick to dry, they are often not as warm or cozy.

The REI Co-op Midweight is a perfect option for skinning uphill on warm winter days. This synthetic wicks well and dries quickly.
The REI Co-op Midweight is a perfect option for skinning uphill on warm winter days. This synthetic wicks well and dries quickly.

Pros
  • Quick to Dry
  • Absorbs less water
  • Durable fibers (doesn't stretch out)
  • Often less expensive
  • Easier to layer with smoother face fabrics
  • Wicks well

Cons
  • Sometimes stinky (even with odor control technology)
  • Petrol-based fibers
  • A smaller range of temperature regulation in comparison to Merino wool
  • Moisture can linger in the fabrics
  • Not as warm as Merino wool

Merino Wool-Synthetic Blend


We haven't reviewed a whole lot of these blends, but the new technology has proven to be pretty great in our experience. This fabric blend features both Merino wool and polyester materials. This high performing material is excellent for a wide range of uses, offering the best of both worlds.

The Capilene Air by Patagonia features a wide range of thermoregulation and amazing wicking power. A perfect option for a Fall hiker or while layering underneath a shell on a blasting cold day.
The Capilene Air by Patagonia features a wide range of thermoregulation and amazing wicking power. A perfect option for a Fall hiker or while layering underneath a shell on a blasting cold day.

Pros
  • A range of temperature regulation comparable to merino wools
  • Super cozy and comfortable
  • More durable than 100% merino wool
  • Amazing wicking power
  • Quick to dry
  • Warm

Cons
  • Less durable than most synthetics
  • Absorbent

Cotton


Cotton is widely used in the construction of cheap base layers because of its low cost. Those who aren't aware of how dangerous this can be in cold weather will typically buy them for themselves and their children. So we're here to educate you.

While cotton is comfortable and breathes well in warm weather, it's dangerous when it's cold outside, especially if you're sweating. Being a highly absorbent material, it doesn't wick it away from your skin but holds it in the material. When that moisture cools, it can cool your body temperature, keeping you cold. You might find your base layers freezing. If you get into severely cold and wet weather, the popular phrase "cotton kills" marches in…it can result in hypothermia, and downhill from there. As a result, don't buy or depend on cotton for cold or wet weather.

Pros
  • Inexpensive
  • Very breathable
  • Feels nice on the skin when dry
  • Easy care
  • Fine around town

Cons
  • Absorbs water
  • Slow to dry
  • Cold in the slightest bit of humidity or cold weather

Choose your Fabric Weight


What are the different fabric weights? There are four different fabric weights to consider when making your long underwear purchase.

A variety of fabric weights exist here with a few key differences in warmth and performance.
A variety of fabric weights exist here with a few key differences in warmth and performance.

Micro Lightweight


The lightest of them, this super fabric is meant for providing sun protection during the warmest season of the year. It is constructed of ultra-thin materials that are perfect for running in the warmer weather of spring, summer, and fall.

Lightweight


Perfect for warm weather that has a little nip in the air. This lightweight option is a tad warmer than the micro lightweight fabric and ideal for year-round use when temperatures are warm. It's also an excellent option for warmer winter days where you might find yourself hiking uphill for a few hours, or for colder nights where you have a few additional layers. If you run warm, it's a great option. But if you run cold, you might want to graduate to the next weight category.

The Smartwool 150 is our favorite lightweight top that's wonderful for cold running or as a layer while hiking uphill in the winter. It also works well as a summer layer high in the alpine.
The Smartwool 150 is our favorite lightweight top that's wonderful for cold running or as a layer while hiking uphill in the winter. It also works well as a summer layer high in the alpine.

Midweight


A versatile weight that is perfect for a plethora of uses. It will keep you warm with a proper layering system in winter storms down to double negative digits. On warmer days, it can be worn on its own as a long-sleeve top. Great for year-round use.

The midweight WoolX Hannah is a great example of a 100% merino wool midweight base layer.
The midweight WoolX Hannah is a great example of a 100% merino wool midweight base layer.

Heavyweight


If you plan on hitting the coldest temperature on Earth, a heavy (or expeditionary) weight layer is best. Suited for frigid temperatures and frigid conditions, this layer is very thick and can be worn as an insulating shirt in cooler conditions. As a super warm base layer, it's not really functional for anything less than the coldest temperature out there, unless you want to wear it on its own as a warm insulating top. They can also be useful for sedentary activities (ice-fishing, anyone?).

Fit & Style


You know that saying "fits like a glove?" Well, that applies here. Base layers are meant to fit close to the skin and shouldn't be too fit nor too baggy. This enables effective wicking and warmth over time. Also, you want to make sure the arms and torso are long enough to cover all your skin. It shouldn't ride up while moving, and ideally, it's easy to layer underneath other layers. The takeaway? If the fit doesn't feel right, don't buy it.

If you're unsure about ordering online, make sure you purchase from a dealer with an easy return policy. This way, you can try things on and send them back if you don't like them.

Also, choose a style that you prefer. The most popular is crew cut, zip neck (with varying lengths of zipper), and hooded options. Crew cuts are a nice option as they don't have a collar on the shirt, and are fairly low profile, hiding underneath another layer. These are great for situations where you may not require additional neck coverage or if you have a variety of other layers already.

A great zip neck layer.
A great zip neck layer.

A zip neck offers a collar and a little more warmth (and ventilation) and protection from the elements by providing insulation to the neck. These are quite versatile, as they can be zipped up in colder weather or unzipped to release heat as temps or activity warms up. Different zipper lengths (½ zipper v.s ¼ zipper) offer access to layers you might stack underneath the base layer top. A hooded option is the warmest and by far the most protective. These are awesome tops if you plan on wearing it on its own, or you don't already have a layer with a hood. These aren't the greatest if you're layering, and you already have a jacket with a hood and an insulating layer with a hood. This might add a little too much bulk.

We appreciate that this crew cut base layer doesn't rise up when we bring our hands up to the sky.
We appreciate that this crew cut base layer doesn't rise up when we bring our hands up to the sky.

Features


What features should you consider? Long underwear tops come with a diversity of features. Some are super simple, while others come loaded with thumb loops, hidden pockets, hoods, and more. Here we explore a plethora of features that you should consider in your purchase.

Thumb Loops are nice to have because they create an anchor point for your sleeves. Some people love them, while other people hate them. Regardless, they are an excellent addition that makes the layer more versatile. When layering over other tops, you can slip your thumb into the loop to help pull down the fabric of the arms.

The thumb loops are a feature only found with the Patagonia Capilene Midweight Crew. A great extra for pulling on layers and keeping the layer in place.
The thumb loops are a feature only found with the Patagonia Capilene Midweight Crew. A great extra for pulling on layers and keeping the layer in place.

Pockets are sweet, but can also add a little bulk. A little stash place for car keys, credit cards, or Kleenex is quite convenient while out on a jog around town. Our testers liked them for long trail runs and skinning adventures in the mountains. Sometimes they are located in a hidden pocket on the hem while other times, they might be found on the arm or breast.

Stash pockets are sweet! The Arc'teryx Rho was the only top that had an extra stash pocket. Super handy for keys  cash  or whatever little extras you might need on the trail.
Stash pockets are sweet! The Arc'teryx Rho was the only top that had an extra stash pocket. Super handy for keys, cash, or whatever little extras you might need on the trail.

UPF (Ultraviolet Protection Factor) might be another factor to consider when purchasing a base layer. If you plan on being in a super sunny spot like a glacier or the desert, UPF might serve you well. Ultraviolet light can penetrate through most thin fabrics and can still cause some sun damage. So if you're interested in protecting your skin or you are sensitive to the sun, find a layer with a UPF factor of at least 40+.

Hoods are another feature to consider when looking at a base layer. Most don't come with a hood as they are intended to go beneath all your clothes and might add extra bulk; however, a hood also adds versatility.

Base layers are great to wear either on their own or under several layers. Pictured here is a bachelorette hut trip on Red Mountain Pass in Colorado and a classic way OGL gets out to test base layers side-by-side!
Base layers are great to wear either on their own or under several layers. Pictured here is a bachelorette hut trip on Red Mountain Pass in Colorado and a classic way OGL gets out to test base layers side-by-side!

Conclusion


When considering the purchase of your next base layer top, consider what you demand in the performance of your top. What fabric type, weight, and features are right for you? Make sure the fit and style are exactly what you are looking for.


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