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There’s nothing worse than feeling too cold when you’re out and about, and a layer of thermal underwear under one of the best winter coats for women can easily make the difference between a comfortable walk and a freezing, miserable trudge. What’s more, today’s high-tech thermal fabrics are thin and versatile enough to blend in with the rest of your wardrobe, making them excellent winter staples as well as base layers.
The best thermals for women work to conserve body heat while regulating your temperature, so you don’t get sweaty and uncomfortable. A must for skiing or hiking in cold climates, thermals and base layers can also make day-to-day life cosier during the winter months. They aren’t just for outdoor wear, however - amid a cost of living crisis, many of us are seeking ways to keep warm when working from home without reaching for the thermostat, and thermals are an excellent solution, especially when you pair them with the best heated throw.
Whether you’re shopping for discreet everyday layers, budget-friendly thermals for working from home or super-insulating skiing and adventure gear, the Mumsnet community has you covered. We’ve gathered the wisdom of the largest online network of UK parents to bring you our pick of thermal tops, leggings and base layers. Plus, if you're looking for other ingenious (and cheap) ways to stay warm at home in cold weather, we've also compiled guides to the best draught excluder, the cosiest kids' blanket hoodie, as recommended by discerning Mumsnet users.
Uniqlo Heattech Scoop Neck Long Sleeved Thermal Top
Choice of colours available
Soft, stretchy and comfortable
A low neckline can easily be worn under other clothing
Not suitable for tumble drying - however, it dries quickly
RRP: £15 | Material: 38% polyester, 30% acrylic, 20% viscose, 12% elastane | Sizes available: XXS to XXL
When it comes to reliable and effective base layers, Mumsnet users couldn’t speak more highly of the Uniqlo Heattech range, which is not only available in a range of colours and styles but comes with an affordable price tag too.
Lightweight enough to wear under everyday clothes, yet warm enough to really feel the difference, it’s no wonder they’re so popular. This long-sleeved scooped neck top is versatile enough to wear on its own, but thanks to its low neckline is also ideal for layering under a jumper or shirt for the ultimate cosiness.
Made from a polyester and acrylic mix, the fabric is soft, stretchy and moisture-wicking, whilst also being supremely comfortable. A must-have winter essential.
Related: The best heated gloves for warm and cosy mitts
Decathlon Women's Ski Base Layer Top
Simple, fitted design
Lightweight enough to layer
Brushed interior for warmth
Some reviewers felt the quality could be better
RRP: £8 | Material: 100% polyester | Sizes available: XS to 2XL
If you need to pick up some thermal base layers but are on a more limited budget, Decathlon is a great place to start. Their affordable thermal base layer top comes in a choice of black and white - ideal for teaming up with their ski base layer bottoms and a pair of the best women's slippers for complete coverage when working from home in cold conditions.
Long-sleeved and lightweight, with a flattering fitted shape, the crew neckline on this top makes it ideal for wearing alone, whilst also being discreet enough to layer under your winter woollies on particularly chilly days. We love the brushed interior and flat seams, although whilst it’s moisture-wicking, some reviewers felt it was a little on the thin side.
Related: The best electric blankets according to Mumsnetters
Lapasa Women's 100% Merino Wool Base Layer Set
Includes top and leggings
Choice of colours
Made from 100% merino wool
A few reviewers found the leggings too short
RRP: £70 | Material: 100% merino wool | Sizes available: XS to XXL
While this set may seem pricey, it includes a long sleeved top and a pair of long johns, so it actually works out decent value for money and has you fully covered – literally. Both pieces are crafted from 100% merino wool, which is super soft against the skin and offers excellent comfort and warmth.
A few reported that the leggings were quite long, so if you're tall, you may want to go for something else, but overall these are a fantastic buy, and we love that they come in a good range of sizes and colours. On icy days working from home, we'd pair them with a hot water bottle for extra toastiness.
Mountain Warehouse Merino II Women’s Baselayer Pants
High-performance merino wool
Super soft and comfortable
Lightweight and breathable
Costly at full price
RRP: £35 (on sale from £60) | Material: Merino wool 80%, polyester 20% | Sizes available: UK sizes 6 - 24 |
For seriously toasty thermals, merino wool is certainly the best choice of fabric, providing warmth and protecting you from the elements without feeling bulky or making you sweaty and overheated.
These Merino Women’s Pants are made from naturally breathable high-quality wool to keep you warm and comfortable in all conditions, making them a practical choice for winter walks, hikes or everyday wear. The elastic waistband ensures they’ll stay put even when you’re at your most active, whilst the lightweight material makes them easy to store and quick drying when washed.
Related: The best thermal curtains for insulating your home
M&S Collection Heatgen Thermal Long Sleeved Top Two-Pack
Heat-retaining base layer
Soft and stretchy fit
Lightweight enough for layering
All the colour options (except one) are quite dark
RRP: £25 for two | Material: 66% acrylic, 28% viscose and 6% elastane | Sizes available: UK size 6 - 22
When there’s an unpleasant chill in the air, a thermal top layered under your usual clothes can help trap heat and keep you warm and comfortable. Snug yet stretchy, these lightweight Heatgen Thermal Tops from M&S come with long sleeves and an attractive scooped neckline that makes a perfect base layer, retaining heat from your body whilst feeling super soft against your skin.
They wash well at 40°C and dry quickly, but thanks to the handy two-pack, you can have a constant cycle so you won’t get cold when one’s in the wash. If you prefer a thicker design, M&S also offer similar tops in the Heatgen Plus range, even warmer for when the temperatures drop below zero.
Choice of thicknesses for all weather conditions
High-performance merino wool
Moisture-wicking to prevent sweating or overheating
RRP: £45 | Material: 100% merino wool | Sizes available: XS to XL
Mumsnet users couldn’t speak more highly of Icebreaker thermals, which offer high-quality merino wool fabrics and are available in a range of thicknesses to suit every type of weather condition. This all-purpose base layer top is made from a breathable 100% merino wool which feels super soft to the touch. The high-performance fabric is moisture-wicking - helping regulate body temperature in all weather conditions and prevent sweating or odours.
The number 175 refers to the weight of the wool - in this case, lightweight - but Icebreaker offers up to 380 for freezing or icy conditions. The stretchy slim fit is flattering on all body shapes, whilst the crew neck can easily become a non-visible layer under jumpers, sweats or even your blanket hoodie on the chilliest days.
Rohan Women’s Merino Union 150 Crew
Soft merino wool
Breathable and moisture-wicking
Flat-locked seams are not visible when layering
Only one colour choice
RRP: £55 | Material: 63% merino wool, 37% polyester | Sizes available: S to XL
Made from superfine merino wool and polyester, this 150 crew base layer is soft and comfortable against the skin, whilst being durable and hard-wearing for colder temperatures.
If you’ve previously found thermals too bulky or found that thicker seams are visible when layered under your clothes, the Rohan 150 Crew is a fab alternative. Unlike some other thermal designs, the seams on this top are flat-locked to prevent bulking or riding up under your clothes. It can easily be worn alone, or under thicker jumpers or fleeces to trap heat and maintain warmth on colder days.
Related: The safest kids' hot water bottle, as recommended by parents
Land's End Women’s Stretch Thermaskin Camisole
Made from lightweight and stretchy jersey material
Ideal for layering under jumpers and cardigans
More feminine and attractive designs than some
Less coverage than crew/tee designs
RRP: £9 | Material: 94% polyester, 6% elastane | Sizes available: UK size 8-20
If you want to wear your favourite lightweight cardigan or slouchy jumper but are worried about feeling the chill, these practical thermal camisoles are perfect for layering, trapping your body heat to ensure you remain toasty warm when the temperatures drop.
Mumsnet users are big fans of Land’s End for their clothing that can withstand the elements. Made from stretchy jersey fabric with adjustable straps for the perfect fit, these moisture-wicking thermals are great for preventing overheating when moving between centrally heated environments and the outdoors, plus they look a little more stylish than some other thermals on our list.
High performance for on the slopes
RRP: £80 | Material: 95% polyamide, 5% elastane | Sizes available: XS to XL
With a striking black leopard jacquard design and white contrasting trim, this stylish high-performance Sweaty Betty base layer is sure to be a popular choice for thermals both on and off the slopes - so long as you’re prepared to pay a premium price tag.
A tight-fitting crew neck top with long sleeves, this seamless design offers excellent coverage without chaffing or rubbing your skin. Thanks to the intelligent moisture-wicking properties, you can also stay toasty warm whilst enjoying an active lifestyle without sweating or overheating. We'd pair with the best heated gilet for a stylish yet toasty on piste look.
Soft and cosy yet less restrictive than slippers
Choice of designs
Too bulky to wear under shoes
More suited to indoor use
RRP: £15 | Material: 58% acrylic, 36% polyester, 5% nylon, 1% elastane | Sizes available: 4-8 UK (One size)
There is nothing worse than having chilly feet, especially when working from home. A pair of thermal socks will ensure your feet are just as warm as the rest of your body, and when it comes to toasty toes, Heat Holders are highly recommended by Mumsnet users.
Whilst they may be thick to wear with shoes or boots, and the non-slip sole grips put them firmly in the slipper socks category, they are perfect for preventing icy toes all winter round, with a thermal tog rating of 2.3.
Related: Keep your mitts warm with the best hand warmers
Camille Women’s Warm Underwear Thermal Winter Shorts
Ideal for additional warmth under skirts and dresses
Elasticated waist for comfort
Subtle printed design
Not the most flattering underwear - but will keep you warm!
RRP: £8 | Material: 100% polyester | Sizes available: UK sizes 8-22
If you still want to wear dresses and skirts as the seasons start to change but aren’t keen on the restrictive nature of thermal tights, these thermal knickers shorts make a great alternative. Providing additional coverage across your thighs, they can trap heat and stop cold air from getting in.
This subtle, feminine design may not be the sexiest underwear you’ll ever own, but with an elasticated waist for comfort and an affordable price tag, they'll make a great addition to your winter wardrobe.
Patra Women’s Pure Silk Thermal Long Johns
Naturally soft and luxurious
Ideal base layer for cold weather
Modal fabrics increase durability
Hand wash or gentle 30-degree wash recommended
Limited to two colour choices
RRP: £60 | Material: Spun silk 10%, modal 90% | Sizes available: XS to 2XL
These Patra silk blend long johns combine the comfort of silk with the durability of modal to create a resilient yet luxurious base layer for chilly weather or outdoor adventures.
If you’re looking for thermals that can keep you warm whilst still feeling soft and luxurious, silk or silk blend thermals make a great choice for layering this winter and are kind and gentle on sensitive skin.
Naturally soft with double-layered cuffs to ensure a good fit, these long-john thermals not only look great but are easy to care for and maintain their shape after washing.
Related: Discover the best dressing gown for women according to Mumsnetters
How do thermals for women work?
Thermal underwear uses premium close-fitting fabrics to keep you warm by trapping air close to your skin, so heat loss from your body is minimised. At the same time, they draw sweat away from your skin, doubling their warming effect. When worn under regular clothes, thermal underwear becomes an effective base layer that can keep your body warm and comfortable, whatever the weather.
Do you wear normal underwear underneath thermal underwear?
Yes, whilst the name can be somewhat confusing, thermal underwear is designed to be worn on top of your regular underwear, and more of a second layer of underwear or base layer before putting on your regular clothes.
How tight should thermal underwear be?
Wear your thermals so they fit snugly, but not uncomfortably so. Most thermal underwear is made from soft and stretchy fabrics, so whilst they may be quite fitted, they should still be comfortable and non-restrictive. You don’t need to size up or down, but instead, opt for your usual dress size.
How to choose the best thermals
Here are some things to consider when choosing the right thermals for you:
Where will you be wearing them? - Are you looking for some thermal underwear to keep you warm and comfortable when working from home, or for winter walks and more intense outdoor adventures? The best fabrics and ultimately the amount you may need to spend will depend upon your activity levels and what features you require from your thermals.
How warm are they? - Some thermals offer a lightweight base layer to wear under your other clothes, whilst some are thicker, warmer or even heat-generating. Consider the environment and the temperatures you will be exposed to, as this may determine the choice of product.
Style and cut - Are you looking to wear thermal underwear as a discreet extra layer under your clothes? Some fabrics and cuts are better suited to layering, including those with a scooped neckline and flat seams. Others are thick enough to be worn on their own but may appear bulky or become restrictive when worn with other garments.
Cost - How much do you wish to spend? As a simple way to keep warm without turning up the central heating, you can pick up thermal underwear with a relatively low price tag. For more high-performance fabrics and features that are well suited to the great outdoors, you may need to spend a little more.
Which thermals are the warmest?
Whilst you can easily pick up some affordable and effective thermals made from other fabrics, such as acrylic or polyester blend, merino wool is by far the warmest and most effective material for thermal underwear, particularly if you are going to be active.
That said, it doesn’t come cheap. If you intend to spend your winter walking or hiking in the great outdoors, they may well be worth the investment. The merino wool options from Mountain Warehouse and Icebreaker are a great place to start.
What type of thermals are best for the UK?
The verdict was fairly unanimous amongst Mumsnetters - Uniqlo’s HeatTech range is the best thermal underwear you can buy today, thanks to its combination of warmth, style and value for money.
How we chose the best thermals for women
Recommendations from real Mumsnet users
Mumsnet users have been sharing lots of ideas on how to keep warm during winter.
First, we sought out the trusted opinions of Mumsnet users, to get their feedback on their favourite thermal underwear including the thermals that they have used themselves and would recommend to others.
We also looked out for any negative reviews, where Mumsetters highlighted products that they felt were poor quality, didn’t wash well, were uncomfortable or simply failed to keep them warm.
Authentic consumer reviews
Then, to bring you our definitive list of the best thermal underwear for women, we thoroughly investigated genuine, in-depth customer reviews on retailer sites such as Amazon, Marks and Spencers and John Lewis to get wider consumer experiences regarding the products on our shortlist.
About the author
Lucy Cotterill is a mum of two and a Content Writer at Mumsnet, specialising in baby/child and lifestyle product reviews and round-ups. Having written product reviews on her own blog Real Mum Reviews since 2012, Lucy loves to research and explore the pros and cons of products, scrutinising reviews and consumer feedback to help people make confident purchases.
Originally from a HR background with a degree in Business Studies, Lucy developed a real passion for blogging and writing when her children were young, going on to write for several online publications including US parenting site Pregistry and the Evening Standard. When she’s not manically tapping the keys of her laptop, Lucy loves nothing more than to cosy up with her Kindle and enjoy the latest thriller, or compete in Nintendo Switch rallies with her daughters aged six and 10.
Why you should trust us
We work hard to provide honest and independent advice you can trust and we spend hours scouring the Mumsnet forums and online bestseller lists to find products that real parents rate.
Transparency is really important to us and that's why we're always upfront about where we find our recommendations. We write about products that we feel offer the best value to most parents – the ones that our users would recommend to their own friends and family.
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