The best base layer should be part of every outdoor clothing system to ensure you're always at the right temperature when you're out and about. Getting hot and sweaty (or cold and miserable) isn't fun under any circumstances, let alone when hiking, camping, or walking in nature. Base layers can ensure you always feel comfortable in your skin.
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.
Base layers tend to be close-fitting, stretchy and comfortable, making it easy to layer up without adding bulk or risking excess fabric getting twisted. The best options can wick sweat away when you're active and provide insulating warmth when the weather's chilly. Read on for our ranking of the best base layers available now.
Best base layers to buy right now
Why you can trust T3 Our expert reviewers spend hours testing and comparing products and services so you can choose the best for you. Find out more about how we test.
The Arc’teryx Rho Hybrid Half Zip Baselayer is a hybrid layer because it employs two different zoned fabrics made from natural and synthetic fibres. The main body utilises Arc’teryx 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.
During the review process, we found the Rho Hybrid to be a top-quality bit of kit that delivers everything you want in a base layer – namely, 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.
You know all about Merino wool, of course, you do, but you should also know that most base layers and T-shirts that claim to use it do so only sparingly. Icebreaker's Tech Lite is virtually all Merino, which makes a big difference. As a base layer, it's soft and warm and wicks away moisture really well, and at 146g, it's in Icebreaker's 150 Ultralight range.
A capsule-wardrobe classic, the Tech Lite is a classic among frequent travellers and 'flashpackers' because it works great as a regular T-shirt (it's not as figure-hugging as most base layers) that's very odour-resistant even in humidity and can be wrung-out in a sink and dried in hours. Whisper it, but you can wear an Icebreaker Tech Lite for days on end without getting wiffy.
The only drawback is that Merino does lack longevity, which is why most brands don't get much beyond 50%; expect it to thin out and get holes after about a year or two of heavy use (top tip: keep it for hikes and holidays only).
The Le Col Thermal Long Sleeve Base Layer is a good example of why you shouldn't judge a book by its cover. It's not like the Le Col Thermal Long Sleeve Base Layer is ugly; on the contrary, it looks pretty neutral yet – due to the ergonomic outline – well fitted and sleek.
The branded collar adds just enough detail to a piece of clothing that otherwise sits under many other layers of tops, jumpers, jackets and the like. No, what I meant about not judging the Le Col Thermal Long Sleeve Base Layer is that it is, in fact, 100% synthetic, but it doesn't feel like a synthetic at all. I don't think I ever wore anything that felt as soft as the Le Col base layer, and that includes my beloved satin underwear.
Also, don't let the fact that Le Col is a cycling brand fool you. The Le Col Thermal Long Sleeve Base Layer is equally as good for running, hiking, or just walking as it is for cycling, and the Coolmax fabric will wick moisture away from the body effectively, regardless of the type of exercise you do.
When the mercury really drops, we think the best base layer around is the Kora Yushu LS crew. It's made with a combination of yak wool and superfine merino that the brand has dubbed 'Hima-Layer' fabric (pause for applause for that pun). We tested the women's version out on a very cold day skiing in Austria and were extremely impressed with it.
It kept us much cosier than our synthetic base layer managed but didn't get at all clammy. All seams are double stitched, and high-wear areas use durable core spun merino yarns for durability. It's close-fitting but not skin-tight. If we were to nit-pick, we wish the body was a little longer.
Dress for the bottom of the mountain, and you're going to get a cold shock 10 minutes later when a cable car dumps you on the peak. Skiing off the tops of icy, freezing mountains on super-cold days requires careful layering, which is why Helly Hansen makes this two-in-one. On the outside is an all-merino wool layer, while next to your skin is a grid-style layer of LIFA Stay Warm Technology fabric.
Thankfully the latter is just as softer against the skin as the former. Keeping merino's moisture-wicking properties and adding an extra-warm layer, this is one of Helly Hansen's warmest base layers that's perfect for any type of activity in cold weather. This one comes with flat lock seams for comfort and a 1/2 zip construction for letting-off a bit of steam. This is the ‘lightweight' version; a ‘heavyweight' version is also available for super-cold adventures.
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 makes some of the best yoga pants around). Of its base layer options, our pick is the Reflex, which uses bamboo jersey that's 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. Flat lock seams and raglan sleeves minimise chafing.
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.
All brands have their own technical fibres, but Columbia's Omni-Heat 3D does look a bit… weird. Its thermal technology is now over a decade old and works by reflecting body heat while also wicking away sweat, but its more recent '3D' update sees a new three-pointed star pattern that keeps the heat in.
However, that pattern is presented in a very shiny, reflective silver, so it looks like the inside of this base layer – aside from strips of breathable polyester/elastane mix fabric on the flanks and spine – is covered in tin foil. It also has a bit of grip, so it's as odd to wear as it is to look at.
Reservations disappear when worn because this base layer's performance is excellent; toasty warm, and dry. We loved the optional thumb loops on the sleeves, and after first-wear, we also loved its unique high-tech look.
You might be surprised to hear that Runderwear does other things than just chafe-free underwear for runners – the brand also manufactures chafe-free tri-suits, chafe-free headbands and neck warmers and also, and chafe-free base layer tops. And not just any chafe-free base layers, but comfortable ones that actually work well for runners.
I guess this last bit is not surprising, given that Runderwear knows exactly how to create fabrics that feel good on the skin and stitching that doesn't rub against the sensitive areas of your body. The Runderwear Long Sleeve Baselayer Top encompasses all the good qualities Runderwear has to offer, as well as adding some really cool features, like the removable mitts, so you don't have to carry running gloves around.
I tested the Runderwear Long Sleeve Baselayer Top running the Vitality Big Half in early March, the weather still being cold, and the running top passed the test with flying colours. It kept me warm in the pit at the beginning, and thanks to the moisture-wicking and dynamic heat control technologies, it wasn't too warm later in the race, either. The best base layer choice for runners.
What's the best material for base layers?
There are many (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 can be worn for days on end without needing to be washed. For general travel, it's unbeatable. However, it doesn't last long.
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 else should I look for in the best base layer?
Something else to think about when looking for the best base layer for you is ventilation and how it's designed-in. Although you're preparing for the cold, if you're likely to sweat (i.e. you're exercising), it's very likely that even the finest merino wool won't be able to wick away every last bead of sweat. So whatever the material it's made from, a base layer that can be unzipped at the front can allow you to cool down quickly with a burst of cold air. Simple, but effective.