When hiking, you often alternate between periods of intense activity and periods of rest. This can cause sudden rises and falls in body temperature, which may put your health at risk. The role of the base layer and thermal underwear is to regulate body heat and wick away sweat. That’s why it matters to choose the right base layer for hiking. Read our advice below.
Choosing base-layer materials
Natural fibres
Natural-fibre clothing, made from materials such as wool, merino wool or bamboo, is widely used for hiking. It provides natural warmth, is lightweight and feels soft. It also does not irritate the skin and has natural antimicrobial properties, helping to manage odours. However, it can be fairly delicate and may take longer to dry than synthetic-fibre clothing.
We recommend a natural-fibre base layer for multi-day hikes. You can also wear one on hikes that alternate between activity and rest.
Avoid cotton as a base layer for hiking. It is not breathable and absorbs the moisture your body produces.
Synthetic fibres
Fibres such as polyester, polypropylene, polyamide and elastane also have many advantages. Garments made from them dry faster than natural-fibre clothing, are more durable and are easier to care for. However, they are heavier, do not manage odours as well and provide less warmth.
You can wear them on a moderate-intensity hiking trip or a short, intense hiking trip. This gives you an effective base layer without having to put up with odours.
Hybrid clothing
Made from a blend of natural and synthetic fibres, hybrid clothing is another effective option. The materials are placed in different areas of the garment to provide good breathability and regulate body heat.
Why fabric thickness matters
Fabric thickness matters when choosing a base layer. While the base layer’s job is to let your skin breathe and the fleece provides insulation, thickness affects how warm the garment feels. The thicker it is, the more insulating it will be, but the less breathable. Choose your base layer according to your needs and the conditions you expect to encounter.
Fabric weight per square metre is often listed in a garment’s specifications. The higher the figure, the thicker and warmer the garment. Here are some guide figures, which may vary depending on the material:
- Below 150 g/m²: for intense activity or hot conditions.
- 150 to 190 g/m²: versatile year-round use, or for mild to cold conditions.
- 190 to 250 g/m²: moderate activity; ideal for colder conditions.
- Over 250 g/m²: low-intensity activity or very cold weather.
How a hiking base layer should fit
Fit is another important factor when choosing a base layer for hiking. The right fit depends on the activity. If it is too loose, heat escapes, though you have more freedom of movement. If it is too tight, it retains heat better but restricts movement. For hiking, aim for a balance: a base layer that fits close enough to the body while allowing you to move freely.
Finally, consider the seams. More and more base layers are made without seams or with flat seams. These can add comfort by reducing the risk of irritation from rubbing as you move.
Choosing the right base layer for hiking is important: it helps regulate your body temperature. The best option depends on the intensity and duration of your activity and the time of year.
