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How to choose the right thermals

KMD Winter17 NZ Product thermals v2

Want warmth and comfort, minus the bulk? It’s time to invest in some clever engineering and highly advanced technology — with your underwear.

There’s an overwhelming choice of thermal underwear out there, and that’s a good thing. Because each base layer has unique features to help you keep warm and get the most out of your activities — whether you're travelling, skiing, or curled up for the afternoon.

The following guide will get you started, but you should also consider your individual use, activity, and the layers you're going to wear.

Thermals for general cold weather

If your main aim is to hibernate and stay as cosy as possible, PolyPRO thermals will do the trick.

Key benefit: WARM

Best base layer for:

Everyday layering, camping, snoozing on the couch.

How does it work?

PolyPRO consists of hollow fibres that work by trapping air in between themselves. This acts as a layer of insulation to provide you with outstanding warmth. Unlike wool, the fibres in polypro don’t absorb moisture; it wicks moisture away from your skin. It’s also lightweight, and quick to dry — ideal when it’s on the winter washing line.

“I had bought these Polypro thermals last year for my husband and I, so when I needed thermals for my kids I didn't hesitate. Polypro is a great price, dries quickly when washed, comes in a nice range of colours and patterns, and most importantly- keeps us nice and warm as an inner layer,” — Sparassidae, customer review.

Thermals for outdoor activities

Heading off to the ski fields? thermaPLUS thermals are perfect for outdoor activities in cool conditions.

Key benefit: WARM AND DRY

Best base layer for:

Alpine sports like skiing/snowboarding, cold weather hiking, conquering mountain tops. That said, people who really hate the cold also really love thermaPLUS.

How does it work?

It’s as warm as it sounds thanks to the dual knit construction — but with the added benefits of being exceptionally breathable, lightweight, and is resistant to pilling. It’s lightweight too, an excellent choice when you’re going to work up a sweat.

"Love everything about this garment. Excellent on the bike, excellent for running in the cold. Great fit. Highly recommend," — Kathrin, customer review.

Bonus Round: The XT Alziro range features base layers made from merino, PolyPRO and polyester, making it an ideal base layer for mountain sports.

All-rounder thermals

Never want to get out of your long johns? ultraCORE is an ideal all season thermal — it’ll keep you warm, dry and smelling good — with a full range of movement to boot.


Best base layer for:

Travel, camping, cold weather hiking.

How does it work?

ultraCORE thermals are made from a lightweight jersey knit and has a natural, soft feel for that next-to-skin comfort. It’s been specially engineered for freedom of movement so you can scramble, stretch, and high-kick all year round.

It also features permanent antimicrobial protection — that is, it’ll keep your body odour in check. You’ll smell nicer, for longer.

“I bought these for my son to wear trekking in Nepal (he is still there - almost at base camp) he said they are fantastic, very comfortable to wear under his trousers and to sleep in (not sure if they have had a wash ha ha). He is especially pleased with the weight of them, and the wick away feature that keeps him dry and warm. Great product,” — Lori, customer review.

Thermals for travelling

A merino base layer makes an excellent travel companion. It can help maintain a comfortable body temperature in summer and winter, has ‘no stink’ odour resistance (which means less washing on the go) and offers excellent warmth for weight.


Best base layer for:

Travel, everyday layering, hiking, camping.

How does it work?

Merino wool consists of smaller, more flexible fibers which bend when they come into contact with skin — so instead of poking or irritating the skin which wool is want to do — the feeling is one of softness.

These finer fibres also help your thermals maintain their shape, and create tiny air pockets in the fabric that are capable of trapping air warmed by the body — providing a great buffer from the cold. As your body heats up, the moisture stored within the fiber will began to evaporate, cooling the ait between your skin and fabric. Thus, wool can actually keep you cool when you’re hot, and warm when you’re cold. Magic!

“I bought this to wear over in the European winter and it was perfect! Didn't sweat too much and it didn't smell at all! So light and easy to travel with!” — discobezza, customer review.

Choosing the right thermals is all about ‘fit for purpose’. Consider your own comfort, what you want your thermals to do (besides keep you warm obviously), and how versatile they’ll be for you in the long run.