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The best base layers to keep you warm, tried and tested
These top-performing layers are ideal for hiking, running and skiing
Tested by Yanar AlkayatFormer Fitness Group Testing Manager
Research shows that taking your workouts outdoors has a positive effect on both physical and mental health, including improving your sleep quality, mood and self-esteem. The only issue is the predictably unpredictable Great British weather, which is why it’s worth investing in one of our experts’ best base layers.
These tight-fitting tops provide a layer of protection against chilly conditions and help keep your body at its optimal temperature while you move. Most feature a breathable, sweat-wicking material to keep you cool and dry.
To ensure you stay on track, whatever the weather, our experts at the Good Housekeeping Institute trialled a range of market-leading base layers, wearing them for various outdoor sessions. Below are our winners at a glance but keep scrolling for our detailed reviews.
Best base layer for HIIT sessions
Icebreaker Women's BodyfitZoneTM Merino 150 Zone Long Sleeve Crewe Thermal Top
Read review
How we test base layers
The Good Housekeeping Institute tested 29 base layer tops. We sent them out to our panel to try in the wild and each one was worn for at least three outdoor workouts.
Panellists gave feedback on how the tops felt before, during and after each session, telling us whether they kept them at an optimal body temperature, absorbed any sweat and allowed them to move freely. Fit, comfort and design were also considered. Our winners are marked with the GHI Approved logo.
It’s part of the job for our health and wellness editors to try all the latest fitness apparel, including base layers. So, we’ve also included their personal recommendations for keeping warm while exercising outdoors in our editors’ picks section below.
Score: 91/100
If you're regularly exercise outdoors, you’ll love our winning base layer’s array of features, including thumb holes, hi-vis design features and pockets.
Featuring the brand's ‘Dri-Fit’ tech, Nike claims this top will keep you dry as you move, and our testers confirmed that it reliably wicked away sweat. It was comfortable to wear and not at all clammy – a great design with a mid-range price tag.
Key specifications
| Material | Recycled polyester, elastane |
|---|---|
| Sweat-wicking | Yes |
| Thumb holes | Yes |
| Pockets | Yes |
Score: 89/100
Staying warm is the aim of the base layer game, but so is staying dry when you get your sweat on. This top’s antibacterial, breathable fabric not only kept our testers comfortable during their workouts but also performed brilliantly in the sweat-wicking stakes.
It scored bonus points for staying in place as our panel tackled burpees, too.
Key specifications
| Material | Merino wool |
|---|---|
| Sweat-wicking | Yes |
| Thumbholes | No |
| Pockets | No |
Icebreaker Women's BodyfitZoneTM Merino 150 Zone Long Sleeve Crewe Thermal Top
Score: 86/100
Mention body mapping tech when it comes to a piece of workout kit and you’ve successfully caught our attention. Basically, the top is designed with zones, each with the ideal thickness, ventilation and flexibility for that part of the body.
Made with 83% Merino wool, this base layer has a slightly steeper price tag. But, excellent breathability and sweat-wicking capabilities, whether squat jumping or walking the dog, earned it a big thumbs up from our panel.
Key specifications
| Material | Merino wool (83%), nylon (12%), elastane (5%) |
|---|---|
| Sweat-wicking | Yes |
| Thumb holes | Yes |
| Pockets | No |
Helly Hansen LIFA® Merino Midweight Long-Sleeve Base Layer
Score: 85/100
Heading out for a casual bike ride or ramble? We've got your perfect base layer. Our panel was impressed by this top's temperature-regulating design, saying it felt pleasingly warm to wear, and they loved the choice of patterns.
Some found the torso and arms too long, but this will appeal if you're taller. Opt for one of our synthetic picks if you’re planning a gruelling HIIT session, as you may find this too sweaty, but it’s a great mid-weight buy.
Key specifications
| Material | Merino wool, polypropylene |
|---|---|
| Sweat-wicking | No |
| Thumb holes | No |
| Pockets | No |
Score: 83/100
Reasonably priced given its sustainability credentials (it’s made from 100% recycled polyester fibres), this top is best kept for strolling round the park or popping to the shops in wintery weather.
Our testers likened the comfy inside lining to a woolly jumper, so don’t expect it to have the breathability of more active base layers. Plus, the V-neck design exposes more skin than high- or round-neck tops.
Key specifications
| Material | Polyester |
|---|---|
| Sweat-wicking | Yes |
| Thumb holes | No |
| Pockets | No |
Smartwool Women's Intraknit Merino 200 Crew
Score: 80/100
Combining the warmth and comfort of Merino wool with the quick-drying capabilities of polyester, this makes a trusty base layer. That said, if you’re after a top for vigorous exercise, it can get pretty toasty. Instead, save it for long chilly rambles and hikes – with a pub pitstop, of course.
Key specifications
| Materials | Merino wool (52%), polyester (45%), elastane (2%), polyamide (1%) |
|---|---|
| Sweat wicking | Yes |
| Thumb holes | No |
| Pockets | No |
The North Face Women's Easy Long Sleeve Top
Score: 71/100
Our testers found the design flattering, but some complained about its poor sweat-wicking ability, which left them feeling cold and damp. Others found the fabric a little restrictive and lacking in give.
That's why this is a good option to wear during warm-ups, before you get your real sweat on. Or save it for leisurewear; its North Face branding makes it one of the most stylish pieces on our list.
Key specifications
| Material | Polyester |
|---|---|
| Sweat-wicking | Yes |
| Thumb holes | No |
| Pockets | No |
Editors' picks
Sweaty Betty is known for combining prettiness with practicality, and this eye-catching pink base layer is no exception. The seamless design feels comfortable and breathable to wear, with mesh panels for extra ventilation in the sweatiest spots. The added thumbholes make an extra cosy addition, too.
If the bright pink or eye-catching turquoise colourways aren't your thing, there’s always black or navy to choose from too.
Key specifications
| Material | Q-SKIN by Fulgar® |
|---|---|
| Sweat wicking | Yes |
| Thumbholes | Yes |
| Pockets | No |
Enter any UK gym and the majority of people will be wearing something from Gymshark. The brand – which features in our best sports bra and best gym leggings round-ups) creates durable, affordable and stylish fitness gear, and this base layer encompasses all three.
As the name suggests, it’s designed to sculpt your body without being too tight or restrictive. The two thumbholes add an extra layer of comfort and also protect your palms against calluses if you wear it during lifting sessions.
Key specifications
| Material | 93% Nylon, 7% Elastane |
|---|---|
| Sweat wicking | No |
| Thumbholes | Yes |
| Pockets | No |
This thermal layer from Free People seems much too stylish to be covered up as a base layer, but it’s good to have on underneath when you hit the slopes (and it will keep you cosy for the après ski).
We love the leopard print, but there are also gorgeous paisley and flowery designs to choose from. Our lifestyle writer, Madeleine loves hers so much, she wears it as an everyday top.
Key specifications
| Material | Cotton |
|---|---|
| Sweat wicking | No |
| Thumbholes | Yes |
| Pockets | No |
This extremely lightweight, half-zip layer is essentially a second skin, adding an extra layer of warmth while still being breathable. It’s made with a blend of Naia material, which is ultra soft on the skin, and bamboo viscose, which is super effective at wicking away moisture.
Not only does it look and feel good on the skin, it’s also kinder to the planet. Compared to fossil-fuel based synthetics, BAM’s bamboo material is made from natural raw materials, which the brand claims have a much lower carbon footprint than cotton or polyester.
Key specifications
| Material | 64% Bamboo Viscose, 29% Cellulose Acetate (Naia™), 7% Elastane |
|---|---|
| Sweat wicking | No |
| Thumbholes | Yes |
| Pockets | No |
What is the best fabric for a base layer?
No matter which elements you’re battling, the aim of a base layer is to regulate your body temperature while avoiding that clammy feeling. With that in mind, finding the right fabric is key.
Cotton is a poor choice; it can draw too much heat away from the body and take too long to dry after you've worked up a sweat. Instead, you’ll find that most base layers are made from moisture-wicking synthetic material or warm yet breathable Merino wool. Below, we've outlined the pros and cons of each.
Merino wool
What is it? Fear not, layers made from this fabric won't be the same as your favourite woolly jumper. Merino wool is lighter than traditional wool, and its temperature-regulating properties make it perfect for base layers.
Pros: The fibres keep you cosy in colder climes by insulating your body, so turn to this material for skiing and snowboarding. It helps to draw away sweat and is naturally antibacterial, keeping odours at bay.
Cons: This is a premium fabric with a premium price tag to match. Some of our testers also found it less comfy to wear than some synthetic tops.
Synthetic material
What is it? Here, ‘synthetic’ refers to any man-made material, such as polyester or polyamide.
Pros: Synthetic base layers tend to be affordable, lightweight and easy to wear. They can feel similar to Lycra, making them a good fit for activities requiring a wide range of motion, such as HIIT.
Cons: Lacking antibacterial qualities, synthetic materials are likely to trap sweat and smell if they’re not washed straight after wear. They’ll keep you warm, but not as toasty as Merino wool tops, so save them for slightly milder weather.
Should a base layer be tight or loose?
Fit is also important, but it depends on your preferred outdoor activity. Tighter tops will trap more warmth, but opt for a looser cut if freedom of movement is a priority or if you’ll be wearing it for several hours.
Bear in mind that, in general, the closer a base layer fits to your skin, the better job it will do of absorbing moisture.
Style comes down to personal preference, but features such as pockets, thumb holes and patches of mesh or breathable fabric for ventilation may prove useful.
The verdict on base layers
Simple, stylish and brimming with useful features, you can't go wrong with our top-scorer, Nike's DrifFIT running top.
If you're after a top that excels in the sweat-wicking department for your early morning jogs, look to Mountain Warehouse's merino top, our runner-up.
If you're after a good, affordable option for everyday wear in winter, opt for this Odlo Activewear Base Layer.
Why you should trust the Good Housekeeping Institute
When it's cold outside you’ll often find our senior health and wellness writer, Priyankaa Joshi, sporting her base layers on her hikes, runs and Saturday morning strolls for coffee (she wears our winner from Nike). So, she knows exactly what to look for from a top performer.
Priyankaa worked with the GHI's former fitness testing manager, Yanar Alkayat, to make sure our testing protocols covered everything you need to know about the best base layers before buying.
We also sent each product out to a panel of keen exercisers to put them through their paces during the winter months, so you can rest assured they won't let you down on chilly adventures.
Priyankaa is our sleep and wellness expert, specialising in expert-tested reviews and roundups on the latest health and fitness products. From walking boots to running machines, Priyankaa has written about hundreds of products and is passionate about providing in-depth, unbiased reviews. Plus, as an avid runner and gymgoer, she knows exactly what to look for when finding the right gymwear, fitness tracker or earphones.
Priyankaa has an MA in Magazine Journalism from Cardiff University and over five years’ experience in health and fitness journalism. Priyankaa has written for Stylist’s Strong Women Training Club, where she regularly wrote about diversity in the fitness industry, nutrition tips, training advice and her experience completing various fitness challenges. She has also written for a variety of publications including Business Insider, Glamour, Bustle, Metro, HuffPost UK, gal-dem and more. Outside of work, Priyankaa can usually be found trying out a new gym class, seeking out London's best eats or watching a Spanish TV show in a bid to keep up her language skills.
Madeleine is our Lifestyle Writer, specialising in expert-tested reviews and round-ups on the latest beauty Beauty and Health & Wellness products. From skincare to protein powders, Maddie is committed to providing honest and helpful reviews to help guide readers to the best product for them. Maddie has a BA in English Literature and Language, which stemmed from her lifelong interest in reading and writing. She started her post graduate life at Hearst UK within a marketing capacity, which quickly turned into a desire to fulfil a writing career.
When she is not writing about the latest expert reviewed products, you can find her rifling through vintage shops or car boots, reading a print magazine, or capturing portraits on her film camera.
Yanar was our former health and wellness tester.
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