Best base layers 2020 for running, cycling, hiking and stargazing

The best base layer is a simple thing – it sits next to the skin comfortably, wicking sweat away, while providing insulating warmth in the winter, or cooling in the summer. Sound like magic? Well, it is a bit. But whether you’re running the Marathon des Sables, climbing the Torres del Paine in winter or walking the dog, a good base layer will keep you comfortable and (relatively) happy. 

Although there are all manner of ingenious hybrid materials used in base layers, from carbon fibre to silver, the general rule of thumb is that natural materials (such as merino) are warmer by weight, more comfortable and absorb less body odour, while artificial materials tend to be more abrasion resistant and easier to engineer and body map (thus lighter and compressive). However, while design is almost everything in base layers, there is also nowhere to hide cheap materials or poor manufacturing, so you’ll very much get what you pay for.

• Need a base layer for running? Check out our best running shoes list
• Prefer running in the wild? We have the best trail running shoes guide too
• Like a slower pace? We have the best hiking boots for your next adventure

How to choose the best base layer for your needs

Base layers are made out of two main materials (generalising a bit here): merino wool (from Australia and New Zealand’s merino sheep) or synthetic fibres. Merino wool retains heat, it’s breathable so 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. 

The other choice is a synthetic base layer, which use various polyester blends that are also breathable, but perhaps not quite as warm as merino. In practice, many base layers use a mix of merino and synthetics.

One thing to remember when looking for the best base layer for you is design-led ventilation. 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 everything. So look for a base layer that can be unzipped at the front to allow you to cool down quickly with a burst of cold air.

Here's our guide to buying the best base layer no matter what activity you're undertaking.

• Best winter running gear: tackle the elements in style
• Best compression socks for running: knee-high socks to help you stay injury-free
• Best compression tights: running tights and gym leggings for all fitness enthusiasts

The best layers, ranked

• Buy the Le Col Thermal Long Sleeve Base Layer directly from Le Col

The Le Col Thermal Long Sleeve Base Layer is a good example of why you shouldn't judge a book by its cover. 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 likes.

No, what I meant about not judging the Le Col Thermal Long Sleeve Base Layer is because 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.

There was a time when Icebreaker’s merino wool base layers were super-expensive and peerless in their ability to wick away sweat and yet stay sweet-smelling for days. With the proliferation of merino wool, that’s no longer true, and Icebreaker has now pivoted to also being one of the best value brands around.

The slim fit 175 Everyday Crewe is something of an all-rounder. A long-sleeve base layer, it’s warm and wicks away sweat well, doesn’t smell, and dries in hours. So as well as being a base layer in winter, it can also be at the core of a capsule wardrobe for travel in warmer climes.   

• Buy the Runderwear Long Sleeve Baselayer Top directly from Runderwear

You'd be surprised to hear that Runderwear does other things than just chafe-free underwear for runners. They also manufacture chafe-free tri-suits, chafe-free headbands and neck warmers and also, 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 feels 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 the dynamic heat control technologies, it wasn't too warm later in the race either. The best base layer choice for runners.

A simple classic Merino wool layer for all occasions, the Finisterre Eddy is an understated baselayer champion. Finisterre’s dedication to materials gives you full supply-chain traceability as well as mulesing-free Merino, both best for peace of mind. 

Long sleeves add warmth in the cooler months, and protection in hotter climes, while the forward-facing shoulder seams increase comfort. Merino is naturally odour-combating, as well as temperature regulating and comfortable next to the skin to boot. Designed in the UK and manufactured in Portugal, the Eddy is a homespun winner. The only thing that might put some people off is the looser fit. 

The North Face Men's Sport Long Sleeve Zip Top has a seamless design to reduce unnecessary chafing and discomfort during exercising. The special body mapped ventilation ridges, holes and patterns create an effective moisture management technology that wicks away sweat but keeps your muscles warm.

This base layer is fully synthetic which might put some people off, since you won't get the benefits of natural merino wool yarns. In the same time, the mix of synthetic fabrics used for the The North Face Men's Sport Long Sleeve Zip Top makes it an excellent compression top for people who don't like compression tops.

In a true The North Face fashion, the materials used in the base layer are sourced responsibly; not sure where you'd source synthetic fabrics though? Regardless off this, The North Face Men's Sport Long Sleeve Zip Top will keep you energised fresher for longer, whether you run or hike this winter.

At the top end of the technology scale, the Megmeister DRYNAMO Warm Long Sleeve Base Layer is all artificial cunning and ingenuity. A polypro/elastane mix gives four-way stretch and completely seamless finish for a snug compression fit – ideal for preventing chafing. That’s also why there are no labels inside, a move other high-end base layers could learn from too. 

Polypro base layers offer excellent wicking and a certain amount of water repellency, as well as a robust build quality, but on the downside they can absorb body odors over prolonged use. The Megmeister has both Anti-odour and antibacterial functions baked in to combat this, however. For high-energy activities such as running or cycling, this is a strong contender. 

The brand Canterbury might be synonymous with rugby but their products can be used outside the field, too. Thermoreg base layers use specially-designed fabric technology that regulates temperature and wick moisture to the surface to keep you dry – a feature that comes in handy when hiking or hitting the gym too

An antibacterial finish makes it tough for odour to cling, while the quick drying fabric means they’re ready faster after a wash. Offset side seams allow full range of movement and the underarm gusset provides additional comfort.

Since it was designed for rugby players, the sizing-range is quite generous: it goes from extra small all the way to 4XL, so even people with larger frames can enjoy the benefits of the Canterbury Thermoreg Long Sleeve Base Layer.

Here’s a product that demonstrates the advantages of combining the properties of merino wool and ‘technical’ fibres (read: polyester). A two-layer construction with flatlock seams, the Lifa Merino 1/2 Zip has 100% merino wool on the outside and a layer of Lifa synthetic polypropylene fabric against the skin. 

It’s thus really warm, so ideal for skiing, but when you get down the mountain into warmer temperatures – and you’ve got a sweat on – its wicking properties are boosted by that 1/2 zip for easy and quick do-it-yourself ventilation.  

The trouble with base layers is they’re only one part of the layering system that’s so important when out in the cold. The next garments you need to think about, of course, is a buff or scarf, and a hat, which close any gaps around your neck. 

Cue the Aclima WarmWool Men's Hooded Sweater from Norway, which includes a clever balaclava hood that can also be worn as a buff. Or you can simply stow it, using a zip for extra ventilation. Fashioned from an extra-soft 100% merino wool, this base layer is longer than most, too, so easy to tuck-in to trousers. That’s crucial for skiing and climbing.