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This easy trick tells you which merino wool base layer is right for your activity

Here's how to choose the best merino base layer for your outdoor adventures

Man at the top of a mountain wearing a Merino wool sweater
Outdoor Vitals

Choosing the right clothing layers could make or break your adventures in the outdoors. Merino wool is one of the most popular materials out there due to its moisture-wicking and insulating properties. It’s warm and odor resistant and can keep you warm and comfortable. This amazing fabric comes in several different weights that suit varying activities. Fortunately, we’ve got an easy trick to tell which merino wool base layer is right for you.

Understanding merino wool base layer weight

Winter landscape
Ian Schneider / Unsplash

Merino wool base layers, also known as thermal underwear or long underwear, come in various weights, typically categorized as lightweight, midweight, and heavyweight.  That said, some manufacturers don’t tell you what weight their wool is, so your next best bet is to inspect the tags and see if they mention a measurement in grams. This refers to the fabric’s weight per square meter, which you can then use to figure out which category your clothing falls into.

Here’s the breakdown:

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Lightweight base layers (150-200 grams):

  • Warmth: Lightweight base layers provide minimal insulation and are suitable for cool to moderately cold conditions. They are ideal for high-intensity activities where you expect to generate a lot of body heat and need moisture-wicking properties to keep you dry.
  • Versatility: These base layers are versatile and can be used in a wide range of temperatures, making them great for layering for more active winter sports.

Midweight base layers (200-300 grams):

  • Warmth: Mid-weight base layers offer moderate insulation and are designed for colder weather. They strike a balance between warmth and breathability.
  • Comfort: They are often chosen as a go-to option for moderately active winter adventures due to their comfort and warmth.

Heavyweight base layers (300 grams and above):

  • Warmth: Heavyweight base layers are the warmest option and are typically reserved for extremely cold conditions. They provide substantial insulation and are best suited for stationary activities or extreme cold weather.
  • Extreme cold: These base layers are favored by ice fishermen, winter campers, and those braving frigid temperatures for extended periods.

How do I choose my base layer weight?

Yosemite in the winter
Jeremy Bishop / Unsplash

Selecting the appropriate base layer weight depends on a few key factors:

Consider your levels of activity

Consider the level of physical activity you’ll be engaged in. For high-intensity activities like running or cross-country skiing, lightweight base layers are often sufficient. Mid-weight options work well for activities like hiking, while heavyweight layers are better for low-intensity or sedentary pursuits like ice fishing or winter camping.

Check the weather conditions

Think about the climate and weather conditions you’ll be facing. If you’ll be exposed to extreme cold, a heavyweight base layer is a must. In milder conditions, lightweight or mid-weight layers will provide the necessary comfort and warmth.

Look into layering

Base layers are just one part of your clothing system. Consider how you’ll be layering your clothing. If you plan to wear multiple layers, such as an insulating mid-layer and a waterproof outer layer, you may need a lighter base layer to prevent overheating.

Choose based on your personal preference

Ultimately, your comfort is the most important thing. Some people naturally run warmer or colder than others, so it’s essential to listen to your body and adjust your clothing accordingly. Experiment with different weights to find what works best for you. Choosing the right base layer weight is a critical decision when gearing up for cold-weather adventures. Next time you head outside, try this handy trick! We hope it will make your selection a lot easier.

Sarah Joseph
Sarah is a lover of all things outdoors. With a bright sense of adventure and a heart for the mountains, she is always…
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