Base Layer Buyer's Guide

By: Kristin Lauver

Pick a fabric. Select a weight. Choose your weapon to combat cold weather.


There's a lot to consider when you layer up to head out in cold weather. But the key to a reliable layering system is starting with a solid base layer. Some of the most important factors in selecting these garments are the fabric type, fabric weight and fit of your next-to-skin layer.

Let's start with the definition of a base layer, sometimes known as "long underwear." As the name implies, a base layer is the first layer you put on. It should have a snug fit, sometimes called a compression fit, which contours to your body to hold in warmth. Base layers are also responsible for wicking moisture away from the body, allowing other layers to work to maximum effectiveness.

As for choosing the best fabric content, it often comes down to personal preference and which inherent properties are most important to you for a specific outdoor activity.

100% silk base layer.

Polyester (and other synthetics) – It dries quickly, resists stretching and shrinking, and is considered especially durable, lightweight and easy to care for. Made of synthetic fibers, polyester (which also includes fleece) has a reputation for feeling less natural against the skin. But its superior breathable, moisture-wicking and warmth-retaining properties make up for what it may lack in softness. It's machine washable.

Wool – It's flexible and highly durable. Plus, it's an excellent traditional insulator. Wool repels light amounts of liquid on the surface and wicks moisture away from the skin. It also naturally resists odor and is flame retardant. Most wool garments are susceptible to shrinkage and should be dry-cleaned, but technological advancements have made machine-washable wool possible.

Silk – Known for its soft, smooth feel, silk is also strong and moderately abrasion resistant. It's absorbent, so it's not ideal for highly aerobic activities, unless treated to enhance its moisture-wicking ability. While dry-cleaning silk is preferred, it can be successfully hand washed.

Heavy wieght performance base layer.

When it comes to selecting a fabric weight, it helps to keep both outdoor temperatures and your activity level in mind to maintain consistent warmth.

Lightweight – Sometimes called "tech weight" or "silk weight" (not to be confused with silk fabric), lightweight base layers are ideal for high activity levels in cold weather or low activity levels in cool weather.

Midweight – Medium-weight base layers are versatile, offering optimal performance for a variety of activity levels in cold weather.

Heavyweight – Providing intense insulation, heavyweight base layers are ideal for low activity levels in extremely cold weather. And some companies offer base layers in even heavier weights for any activity level in severely cold conditions.

Regardless of fabric type or weight, base layer tops come in a variety of styles, all with a contoured fit. You can choose from crew-neck, V-neck or mock-turtleneck styles with everything from pullover, button-up or zip-up designs. Bottoms are more uniform with little variation other than standard or ribbed-cuff ankles.

Polar wieght performance layer.

But with additional features like down insulation, thumbholes and scent control technology, base layers are becoming increasingly more customizable (and more difficult to choose from based on the basics). So don't be distracted by the extras – fabric, weight and fit will keep you warm.