The Ultimate Thermal Underwear Guide to Stay Warm (and Stylish) in 2025

Posted by Michaela Natter
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Let’s face it: winter can be brutal. But freezing your butt off in the name of fashion? Absolutely not. That’s why thermal underwear is a must-have this season. It’s not the boring, bulky kind from the past. These are sleek, stylish layers that fit your wardrobe well and keep you warm.

In this guide, we explain how to pick the best thermal pieces that keep you warm. They do this without making you feel like you are dressing for a 1990s ski lodge. Whether you’re heading off on outdoor adventures, running errands or hitting the ski slopes, your layering system should start with thermals that are high quality, breathable, and body-loving.

Why You Need Quality Thermal Underwear in 2025

Today’s thermal clothing is designed for much more than warmth. Unlike the thick, scratchy thermals of the past, modern options feature breathable, moisture-wicking fabrics and flattering cuts that fit seamlessly into your everyday wardrobe. It’s about:

Breathability and moisture-wicking properties (no sweat build-up)
Superfine merino wools that regulate body temperature naturally
Lightweight layering systems that support active and everyday lifestyles
Stylish options like thermal vests, thermal tops, and long sleeve thermal tops you can show off

Plus, many styles now feature natural fibres like Australian merino wool and cotton, making them soft, prickle-free, and perfect for sensitive skin.

Wool vs Cotton Thermals: Which One’s Right for You?

Both are essentials, but here’s a breakdown to help you decide:

Wool Thermals

Crafted from Merino wool (often from Australian merino sheep)
Superior moisture absorption and quick dry benefits
Excellent for outdoor activities, including snow sports and hiking
Naturally odour-resistant

Top picks at The Foundation:

These pieces use wool blend fibres to balance softness and performance.

Cotton Thermals

A great option for everyday wear and lounging
Highly breathable with natural comfort
Excellent for layering under jackets or fleece pants

Customer favourites:

How to Style Thermal Underwear Without Looking Boring

Under Your Workwear with Ease

Slip a Long Sleeve Thermal Top under a button-up or blazer. Try the Wool & Silk Ribbed Tank Top as a polished underlayer with trousers and boots.

At Home But Make It Chic

Mix a Thermal Vest or tank with knit pants for a cosy-chic loungewear set. Perfect for running errands or WFH.

Adventure-Ready Layers

Layer a thermal crew or base layer top under your winter jacket. Whether hiking, camping, or just braving windy mornings, these wool layers have your back.

How to Care for Thermals: Wool and Cotton Tips

Use a delicate or hand wash cycle in cold water
Stick with mild, wool-safe detergents (no bleach!)
Lay flat to dry to retain shape and softness
Avoid hangers – fold your thermals neatly instead

With the right care, high-quality thermals from The Foundation can last for many years, often maintaining their softness, shape, and insulation through multiple winter seasons (like our Essential Thermal picks) can last season after season.

Where to Buy Thermals in Australia

Looking for stylish and effective thermal underwear with reliable service and free delivery Australia-wide on orders over $150? We’ve got you.

Explore:

As a family-owned business, The Foundation hand-picks thermal underwear made from premium fabrics — always stylish, always supportive.

Final Thoughts: Stay Warm, Look Good

A great winter outfit starts with the right base. Think: soft ribbed tanks, breathable thermal waffle pants, or our Thermal Waffle Long Sleeve Top — perfect foundations to build your winter wardrobe around. or a thermal waffle long sleeve top that can stand alone. With natural fibres, moisture-wicking fabrics, and flattering designs, you don’t have to choose between function and fashion.

And no need to overspend either — we offer affordable prices and a curated range of essentials you’ll actually wear.

Ready to layer like a pro? Explore our thermal range today.

FAQs

What is the best fabric for thermal underwear?
Merino wool and wool blends are top-tier for warmth, moisture control, and softness.
Can thermals be stylish?
Yes — just look at our lace-detailed cotton tanks or ribbed long sleeves. Style and function meet here.
What makes merino wool thermals so special?
Merino wool comes from Australian merino sheep and is naturally soft, breathable, and moisture-wicking. It's ideal for regulating body temperature and staying dry and comfortable all day.
Are your thermals good for outdoor activities?
Absolutely. Many are crafted for all-day comfort whether you're layering for hiking, snow days or travel.
What sizes do your thermal tops come in?
We stock inclusive sizes from WOMEN XXS to XXL, thoughtfully designed to support and flatter every body. Our customer care team is always here to help you find the perfect fit. designed to flatter every body.