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.
Best base layers to buy right now
Why you can trust T3
Best base layer overall
Weight: 170g/6oz
Materials used: 100% polyester (main), 87% Wool, 13% Nylon (panels)
Fit: Athletic
+ Warm yet lightweight
+ Wicks moisture fast
+ Soft and comfortable
- No thumb loops
The main body of Arc’teryx's Rho Hybrid Half Zip Baselayer utilises the Phasic AR II fabric, a midweight polyester treated with silver ions to neutralise body odour. Meanwhile, underarm panels are made from a blend of natural merino wool and hard-wearing nylon.
We found the Rho Hybrid to be a top-quality bit of kit that delivers everything you want in a base layer – great next-to-skin comfort, decent insulation, and good moisture-wicking performance. That hybrid combination of synthetic fibres and natural merino wool also seems to be a winner, not just in terms of performance but also in keeping things fresher for longer.
Read our full Arc’teryx Rho Hybrid Half Zip Baselayer review
Best base layer for moisture management
Weight: 235g/8.3oz
Materials used: Shell: 70% Merino Wool, inner 30% Polypropylene
Fit: Athletic
+ Warm and wicks moisture fast
+ Soft and comfortable
+ Odour-resistant
- No thumb loops
The Helly Hansen LIFA Merino Lightweight Half Zip Baselayer merges LIFA technology with classic Merino wool for exceptional warmth and moisture control during outdoor activities. Crafted with meticulous attention to detail, it features a soft flap behind the neck zipper and a chin guard for added comfort. The raised collar and lined interior provide extra warmth, while flatlock seams minimize chafing.
The innovative two-layer construction optimises moisture wicking with synthetic LIFA fibres next to the skin and lightweight merino wool on the outer layer. Despite its lightweight design, it offers sufficient warmth for active pursuits in cold climates and maintains durability and shape even after multiple washes.
Read our full Helly Hansen LIFA Merino Lightweight Half Zip Baselayer review
Best base layer for cycling
Weight: TBC
Materials: TBC
Fit: Performance
+ Amazing quality
+ Superb sweat-wicking capabilities
+ Soft to the touch
- Cycling-optimised fit isn't for everyone
The Le Col Thermal Long Sleeve Base Layer is a 100% synthetic garment that doesn't feel like a synthetic at all. It's optimised for cycling, and has a close-fitting aerodynamic fit designed specifically for racing. It dries fast and has anti-odour properties, making the ultimate performance base layer out there for cycling and beyond.
Although the Le Col Thermal Long Sleeve Base Layer is designed for cycling, we found it equally as good for running, hiking, or just walking. It has a shorter cut, mind, so it might not suit larger people due – somthing to keep in mind. The jersey is optimised for conditions from 5-15C, so it's not suited for cold weather riding.
Best budget base layer
Weight: TBC
Materials: Bamboo viscose, cotton, elastane
Fit: Active
+ Sustainably made
+ Thumb loops
+ Breathable, soft fabric
- Quite tight-fitting for recreational use
BAM specialises in clothing made from bamboo, often with other fibres blended in for maximum comfort, durability and performance while still being as eco-friendly as possible (this brand is responsible for some of the best yoga pants around). Of its base layer options, our pick is the Reflex, which uses bamboo jersey with its soft, breathable, sweat-wicking and anti-bacterial.
The design is cut longer in the body and arms to ensure everything stays covered even when you're moving around a lot – there are even thumb loops for when it's chilly. Flatlock seams and raglan sleeves minimise chafing. Even though it's longer to keep your lower back warm, BAM's top is more tight fitting than other base layers in this guide.
Best base layer for hot weather
Weight: 180g (Men's medium)
Materials: Polartec Delta Cooling Fabric
Fit: Athletic
+ Excellent moisture-wicking capabilities
+ Reduced cling
+ Highly breathable
- Feels thicker than standard base layers
ThruDark's short-sleeved base layer caught our attention thanks to its material. Polartec's Delta uses the Fresh Face technology, which is a plant-based, sustainable alternative to traditional textile fresheners and is infused with mint oil to keep you cool even on the hottest of days.
Thanks to the superb moisture-wicking capabilities and more relaxed fit, the Oryon Delta T-Shirt clings less to your body when you sweat. It feels somewhat thicker than other synthetic base layers, but once the temperature starts rising inside and outside the top, you'll soon feel the mint oil-powered cooling kicking in.
Best eco-friendly base layer
Weight: TBC
Materials: bamboo viscose, organic cotton, elastane
Fit: Active
+ Thick enough to wear as a T-shirt
+ Vegan-friendly fabric
+ Soft, stretchy and super comfy
- Could be more breathable
The Finisterre Bora (for men) and Vela (for women) are short-sleeved base layers made from a blend of bamboo and organic cotton designed as a vegan-friendly alternative to Merino wool. The fabric is stretchy, soft and super-comfy to wear, as well as being thick enough to don as a T-shirt and worn on its own.
That thickness has its downsides; the fabric isn't quite as breathable as others we've tried and will probably be a bit warm to wear in hot weather. However, the Vela and Bora still earn their place in our best base layer guide for delivering a versatile, hardwearing and high-quality layer at a competitive price.
Read our full Finisterre Vela/Bora Bamboo base layer review
Best merino base layer
Weight: TBC
Materials: 87% core-spun merino wool, 13% Nylon
Fit: Relaxed
+ Breathable and odour-resistant
+ Lightweight construction
- Short product lifecycle
- Relaxed fit isn't ideal for exercise
Icebreaker's Tech Lite is a classic among frequent travellers and 'speedpackers' thanks to its odour-resistant capabilities and the fact it can be wrung out in a sink and dried in hours. It works great as a regular T-shirt (it's not as figure-hugging as most base layers), and, between you and us, you can wear an Icebreaker Tech Lite for days on end without getting too whiffy.
The only drawback is that Merino does lack longevity, which is why most brands don't get much beyond 50%. Expect this top to thin out and get holes after about a year or two of heavy use (top tip: keep it for hikes and holidays only).
FAQ
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.