Best base layer 2024: top picks for outdoor comfort and performance

Find the best Merino and synthetic base layers to keep you comfortable whatever the weather

best base layer: pictured here, a hiker doing up his hiking backpack straps
(Image credit: Klattermusen)

In winter, having the best base layer is essential for outdoor activities, ensuring comfort in fluctuating temperatures. Whether hiking or camping, these close-fitting layers provide insulation and sweat-wicking properties for optimal performance.

Designed to be stretchy and comfortable, base layers facilitate seamless layering without adding bulk. With our roundup of the top base layers, you'll be well-equipped for any chilly adventure, allowing you to enjoy the outdoors without worrying about discomfort.

As you've probably guessed, the base layer is the first of many thin layers that you can put on or take off as you need to maintain a comfortable temperature; so if you're out hiking, for example, you could add a fleece jacket with one of the best waterproof jackets on top, so you have plenty of options depending on the weather and how much you're exerting yourself.

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What's the best base layer material?

There are many ingenious hybrid fabrics used in base layers, from carbon fibre to silver, but they can broadly be split into two camps: those made from merino wool and those created using synthetic fibres. 

The famous (and expensive) Merino wool is warmer by weight, more comfortable and absorbs less body odour. Merino wool retains heat, it's breathable, so it allows sweat to escape, and as a bonus, it's naturally antibacterial, so it can be worn for days on end without needing to be washed. For general travel, it's unbeatable. However, traditionally, Merino wool fabrics don't last as synthetics.

Though there are many hybrids that use a mix of both, the other end of the spectrum is the wholly synthetic base layer. They tend to use various polyester blends that are also breathable but perhaps not quite as warm as Merino. Artificial materials tend to be hard-wearing and easier to engineer and body map. That means they're generally lighter and longer-lasting. 

What is the warmest base layer material?

Merino wool, by far, is the warmest base layer material. This natural fabric also helps regulate heat better, as well as being swift-wicking and odour-resistant. For the most warmth, look for Merino base layers with 250-300g weight.

Matt Kollat
Section Editor | Active

Matt Kollat is a journalist and content creator who works for and its magazine counterpart as an Active Editor. His areas of expertise include wearables, drones, fitness equipment, nutrition and outdoor gear. He joined T3 in 2019. His byline appears in several publications, including Techradar and Fit&Well, and more. Matt also collaborated with other content creators (e.g. Garage Gym Reviews) and judged many awards, such as the European Specialist Sports Nutrition Alliance's ESSNawards. When he isn't working out, running or cycling, you'll find him roaming the countryside and trying out new podcasting and content creation equipment.

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