Best base layers 2020: top base layers for running, cycling, hiking and stargazing, whatever the weather

How to keep warm in winter? That’s easy – get the best base layer. Whether you’re going running, hiking, skiing, or planning to spend a bit of time outdoors in the Arctic Circle looking for the northern lights, what you wear against your skin makes all the difference. 

A base layer is the layer you wear first before you put on anything else and one that keeps you warm and soaks up your sweat. It traps hot air next to your skin, but a good base layer should also be breathable enough to wick (remove) sweat from your skin. After all, you can’t be wet while simultaneously trying to keep warm. 

Cue a bunch of natural and synthetic fibres that claim all kinds of properties. However, finding the best base layer for you need not be complicated. 

• 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 to wear on 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 jackets
• Best winter running gear: tackle the elements with the best winter running shoes, winter running tops and more

The best layers, in order

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.   

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.

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.