Upgrade your winter wardrobe with sustainable base layers & thermals that are designed to offer maximum warmth and performance – while also being skin-safe, ethically made and eco-friendly.
From moisture-wicking organic cotton to temperature-regulating merino wool, we’ve hand-picked a small but mighty selection of the most eco-friendly and ethically produced sustainable base layers from around the world.
The temperature is dropping, and it’s time to start thinking about your cold-weather essentials for winter! Whether you’re planning a weekend in the mountains or simply need a cozy layer for your daily commute, sustainable base layers and thermals are the perfect solution.
Imagine slipping into a soft, warm base layer that’s not only comfortable but also kind to the planet. Opting for well-made long underwear made with high-quality materials is a great way to showcase your commitment to a greener lifestyle while staying warm and stylish.
The eco-friendly long johns we’ve selected are made from the softest materials like organic cotton, merino wool, and bamboo viscose. And they’re produced using responsible manufacturing processes that reduce waste and environmental pollution.
My top picks for sustainable thermals & base layers…
- Best Overall: Little Spruce Organics
- Best Merino Wool Base Layers: Danish Woolen Delight
- Best Base Layers For Sensitive Skin: L’ovedbaby
- Best Moisture-Wicking Option: The Woolly Clothing
- Best for Outdoor Sports: Merino Tech
And don’t forget about the farmers, herders, and factory workers behind these incredible garments! When you purchase sustainable thermals, you’re supporting fair wages and safe working conditions. It’s a win for everyone involved.
So, as you gear up for the chilly months ahead, consider investing in some good quality sustainable base layers & thermals. They’re an investment that you’ll thank yourself for again and again.
What are sustainable base layers & thermals?
Sustainable base layers and thermals are made from certified organic materials like cotton or wool, grown without toxic pesticides and processed with less water than conventional methods.
They often carry third-party certifications like GOTS and OEKO-TEX, ensuring environmental and social responsibility. These garments also use natural, non-toxic dyes and eco-friendly processing methods.
What are the best materials for base layers?
Organic Cotton
GOTS-certified organic cotton is a top choice for sustainable base layers. Typically, organic cotton is cultivated without the use of genetic modification or pesticides in the farming of the cotton crop.
It can also mean the cotton is processed without the use of toxic chemicals in the manufacturing stage. Organic cotton is also naturally hypoallergenic, making it perfect for those with sensitive skin.
Merino Wool
Merino wool, particularly from organic or certified sources, is another great option for sustainable base layers.
As a renewable resource, sheep produce new wool each year, and this natural fiber is biodegradable at the end of its life.
Merino wool’s inherent temperature regulation, moisture-wicking, and odor-resistant properties, combined with its breathability, allow for extended wear between washes.
Enhanced Sustainable Blends
For the best of both worlds, consider base layers made from sustainable fiber blends.
Merino wool and silk combinations can offer better durability and temperature regulation while still minimizing the need for chemical processing.
Often companies will include a small amount of elastane (spandex) to improve fit and comfort without compromising the primary sustainable material benefits. It’s best to look for options that contain 5% elastane or less.
15 Best Sustainable & Organic Base Layers & Thermals
1. L’ovedbaby
Embrace comfort and sustainability with L’ovedbaby’s women’s organic lounge set.
Crafted from super-soft GOTS-certified organic cotton, this set is gentle on sensitive skin and free from harmful toxins.
The top features a 4-snap front opening for easy breastfeeding, while the tapered waist creates a feminine silhouette.
The legging-like bottoms offer a supportive, slimming fit with tapered ankle cuffs.
Available in beautiful colors that match L’ovedbaby’s organic cotton basics, this set is perfect for lounging day or night.
L’ovedbaby is committed to sustainability, using 91% less water than conventional cotton and ensuring fair labor practices.
price
$60.00
Materials
100% GOTS-certified organic cotton
location/shipping
Designed in California & ethically manufactured in India, ships to Canada, the United Kingdom, Mexico & India
2. Little Spruce Organics
Made in Portland, Oregon, these organic cotton base layers represent the perfect blend of comfort and environmental stewardship.
The GOTS-certified organic cotton is grown without harmful pesticides and processed using low-impact dyes.
The thoughtful design includes flat-lock seams to prevent chafing and a comfortable elastic waistband that won’t dig in during long days outdoors.
These pants excel in moderate temperatures and everyday wear, making them perfect for spring hiking, camping, or as a cozy layer for winter activities.
The breathable fabric wicks moisture effectively while providing just the right amount of warmth.
price
$27.95
Materials
100% GOTS-certified organic cotton
location/shipping
Made in Portland, United States, ships to Canada
3. Nui Organics
Use discount code SKL20 to save 20%!
Elevate your all-season wardrobe with NUI Organics’ women’s Merino silk crew that combines the best properties of merino wool and silk.
These luxurious base layers, produced in New Zealand, offer superior temperature regulation and incredible next-to-skin comfort.
The merino silk blend is able to keep you cool when it’s hot and warm when it’s not.
The rib fabric allows for plenty of stretch while maintaining its shape and color, and the silk adds extra sheen, strength, and a lustrous shimmer to the fabric.
Designed for high-end performance and travel, this top packs down small while maintaining its shape, and the natural fibers require minimal washing.
Price
$88.00
materials
70% organic Merino wool & 30% silk
location/shipping
Made in New Zealand, ships to the United States, Canada & Hong Kong
4. Pact
Use discount code SKL15 to save 15%!
Stay warm and comfortable with PACT’s everyday layering long johns, made with organic cotton in a Fair Trade Certified factory.
Based on their best-selling extended boxer briefs, these long johns provide a soft, breathable, and barely-there feel while still offering an extra layer of warmth.
Featuring a low-rise waist and a snug fit, these long johns are made with stretch fabric for everyday wear.
The full-length design hits at the ankle on most, and the no-roll, smooth flat waistband ensures a comfortable fit throughout the day.
PACT’s commitment to sustainability is evident in their use of GOTS-certified organic cotton, which consumes less water, energy, and harmful chemicals compared to conventional cotton.
Price
$44.00
materials
95% organic cotton & 5% elastane
location/shipping
Made in a GOTS Certified & Fair Trade Factory in India, ships to the United States
5. Maggie’s Organics
Use discount code SKL10 to save 10%!
Experience ultimate comfort with Maggie’s Organics base layer leggings, crafted from a premium blend of 90% organic cotton and 10% spandex.
Designed with ultra-soft, stretchy fabric that moves effortlessly with you, these leggings feature a covered elastic waistband that rests gently at your natural waist. Perfect for layering or lounging, they’re your go-to for cozy, everyday wear.
Since 1992, Maggie’s Organics has been committed to ethical, sustainable fashion. Prioritizing fair trade, regenerative farming, and a people-first approach to creating products that honor the planet and its communities.
Price
$34
Materials
90% organic cotton & 10% spandex
Location/Shipping
United States, ships worldwide
6. Merino Tech
If you’re a serious outdoor enthusiast, the Merino Tech women’s thermal set offers premium performance.
Crafted from the highest-quality Merino wool, this set provides great insulation with an optimal warmth-to-weight ratio.
The set includes thoughtful details like thumb holes and a dropped-back hem, making it excellent for high-intensity winter activities or extreme cold conditions.
Whether you’re braving the cold outdoors or enjoying a cozy evening indoors these thermals will keep you extra warm in even the coldest weather.
price
$99.99
Materials
100% New Zealand Merino wool
location/shipping
Made in New Zealand, ships to the United States
7. Rawganique
Stay warm and comfortable with Rawganique’s 100% organic cotton fleece long johns.
Crafted from specially spun plastic-free organic cotton fleece, these long johns feature an ultra-soft, cashmere-like texture, without the itch.
Perfect as a base layer under overalls and work pants, or as comfy fleece leggings for lounging at home or even venturing outdoors.
Since 1997, Rawganique has been dedicated to creating eco-friendly, biodegradable clothing and home goods using organic, chemical-free materials, all produced sweatshop-free in Europe and the USA.
price
$99
Materials
100% organic cotton double-brushed fleece
location/shipping
Made in Europe, ships worldwide
8. Rambler’s Way
Ramblers Way wool long johns are all about practical luxury.
Made from 100% Rambouillet Merino wool grown and sewn entirely in America, these lightweight long johns provide soft and snug coverage from hip to ankles for next-to-skin warmth, comfort, and protection.
The superfine worsted wool provides exceptional warmth without the itch, and the design features flat-lock seams and a no-bunch waistband for active use.
Ethically sourced from ranchers in Montana, Wyoming, Colorado, Nevada, and Texas, the Rambouillet Merino wool undergoes a unique manufacturing process.
The superfine long-staple fibers are spun parallel to each other to create a clean, smooth, and tightly knit worsted yarn that’s free from the usual fiber ends that cause itching.
price
$140.00
Materials
100% Rambouillet Merino wool
location/shipping
Grown & sewn in the United States, ships to Canada
9. ecoAble
The women’s thermal base layer top from ecoAble is made from a premium blend of 70% organic Merino wool and 30% silk.
It delivers lightweight warmth that feels soft and cozy against your skin. The thin, 190 gsm fabric offers warmth without bulk, making it ideal for layering in cold weather.
The fine rib knit provides a snug, flexible fit for unrestricted movement.
Merino wool is naturally odor-resistant, allowing you to wear it multiple times before needing to wash it.
When it does need a refresh, a simple hand wash will suffice, extending the life of the garment.
price
$63.99+
Materials
70% organic Merino wool & 30% silk
location/shipping
Made in Germany, ships to the United States & select international countries
10. Danish Woolen Delight
Danish Woolen Delight’s HOCOSA organic Merino wool long-sleeve undershirt is a true delight for outdoor enthusiasts.
By combining traditional wool-working expertise with modern sustainable practices, this Swiss brand creates truly exceptional thermal layers.
The incredibly fine Merino wool is sourced from certified organic farms in the Alps. The wool undergoes minimal processing, preserving its natural performance properties while ensuring the finished product remains chemical-free.
Perfect for high-intensity winter activities, this unisex style features a cut that fits both men and women, with broader shoulders and narrower hips compared to women-specific designs.
price
$72.90
Materials
100% GOTS-certified organic wool
location/shipping
Made in Switzerland, ships to the United States & Canada
11. Hemen Biarritz
Embrace sustainable comfort with Hemen Biarritz’s long johns ikar, crafted from certified organic cotton.
Produced in France’s Basque country, these long johns blend traditional craftsmanship with modern design, featuring a cotton button tape and red overstitch for a touch of style.
The medium-weight organic cotton provides excellent temperature regulation, making them perfect for everyday wear or light outdoor activities.
Hemen Biarritz is committed to using GOTS-certified cotton, ensuring greater transparency and traceability when sourcing organic cotton.
Their sustainable production processes ban any dangerous inputs like toxic heavy metals and aromatic solvents.
price
€62.50
Materials
96% GOTS-certified organic cotton & 4% elastane
location/shipping
Made in Portugal, ships to the United States & select international countries
12. Organic Basics
Indulge in the ultra-soft and comfortable core leggings from Organic Basics.
Made with 95% GOTS-certified organic cotton and 5% elastane, these leggings have a snug, body-hugging fit that is great for layering under winter clothing.
Smooth and stretchy, these leggings are designed for comfortable all-day wear.
Organic Basics uses ethical production methods and sustainable materials, such as organic cotton, which is grown without harmful chemicals and has a much lower environmental impact compared to regular cotton.
price
$44.00
Materials
95% organic cotton & 5% elastane
location/shipping
United States, ships to Canada
13. Woolly Clothing
Woolly Clothing aims to make a full Merino life possible by replacing your synthetic garments with better versions made from Merino wool.
Their women’s leggings are the perfect pants for everything from running errands to running up your local trailhead.
Made in Vietnam using Australian Merino wool, these leggings balance performance with urban style.
The versatile mid-weight 320 GSM Merino/elastane blend offers support and breathability for warm temperatures and active pursuits.
While the 100% micron wool provides exceptional softness and durability, making these leggings perfect for travel and everyday wear.
price
$99.99
Materials
95% 18.5-micron Merino wool & 5% elastane
location/shipping
Made in Vietnam, ships to the United States
14. Menique
Embrace the ultimate comfort with Menique’s women’s 250 leggings. These leggings are made for every version of you no matter what activities you love.
The Merino wool is ultra-smooth and hypoallergenic, made without bleaches or dyes, and is supremely soft.
As an added environmental bonus, the undyed yarn leaves no trace and disappears back into the Earth once you’re done with them.
The flexible bottoms offer multi-way stretch and compression with a flattering high-rise fit and a wide waistband of 6cm.
Made from European-sourced Merino wool, these Lithuanian leggings are exceptionally warm for serious winter activities.
The 250g weight provides substantial insulation while maintaining good breathability. And the body fit includes reinforced knees and a high waistband designed for movement.
price
$89.95
Materials
100% Merino wool
location/shipping
Made in Lithuania, ships to the United States, Canada, the United Kingdom & Germany
What are the advantages of choosing sustainable base layers?
Environmental Benefits
By choosing sustainable base layers, you’re actively minimizing your environmental impact.
Organic cotton base layers use 91% less water than their conventional counterparts, while biodegradable materials like merino wool and organic cotton reduce end-of-life pollution. Sustainable production methods also mean minimal chemical pollution from processing and dyeing.
Opting for locally or regionally-produced garments further reduces your carbon footprint by cutting down on transportation emissions.
Social/Ethical Benefits
Sustainable base layers often come with the assurance of fair labor practices and transparent supply chains.
Third-party certifications like GOTS ensure that workers are treated ethically and paid fair wages throughout the production process.
By supporting sustainable brands, you’re contributing to the well-being of farming and manufacturing communities and promoting responsible business practices.
Performance Benefits
Sustainable base layers aren’t just good for the planet, they’re also great for keeping you warm!
Hypoallergenic materials like organic cotton are perfect for sensitive skin, while merino wool and sustainable blends offer natural temperature regulation and moisture-wicking properties.
These breathable, odor-resistant materials keep you comfortable whether you’re cross-country skiing or just crossing the road on your daily commute. They also reduce the need for frequent washing.
Health Benefits
Choosing sustainable base layers means minimizing your exposure to harmful chemicals and toxins.
Organic materials are grown and processed without toxic pesticides or dangerous substances, ensuring that your skin is protected from irritants.
Sustainable, natural dyes and processing methods further reduce the risk of allergic reactions or skin sensitivities.
By opting for eco-friendly base layers, you’re prioritizing your health and well-being while staying warm and cozy.
What certifications should I look for to guarantee sustainable base layers & thermals?
- Global Organic Textile Standard (GOTS): This is a leading textile processing standard that ensures organic fibers are used throughout the supply chain, from growing to labeling.
- OEKO-TEX Standard 100: This certification guarantees that textiles are free from harmful substances, ensuring safety for consumers
- Recycled Content Standard (RCS): This standard verifies the use of recycled materials in textiles, reducing the demand for virgin materials.
- Bluesign Approved: This certification ensures that products are produced in an environmentally friendly and socially responsible manner, with minimal impact on people and the environment.
How do sustainable base layers compare to traditional options?
Sustainable base layers often outperform traditional synthetics in key areas:
- Natural fibers like merino wool offer superior temperature regulation.
- Materials like organic cotton and hemp provide better breathability.
- Sustainable options have natural odor resistance, requiring fewer washes.
- Higher initial cost but longer lifespan makes them cost-effective.
- Better for sensitive skin due to fewer chemical treatments.
What’s the best way to care for your sustainable base layers?
General care tips that extend the life of your sustainable layers include:
- Wash in cold water on a gentle cycle.
- Use gentle, eco-friendly detergent.
- Air dry when possible.
- Turn garments inside out before washing.
- Store folded, not hanging, to maintain shape.
- Spot clean when possible to reduce washing frequency.
- Repair small holes immediately to prevent spreading.
Are sustainable base layers as warm as traditional synthetic options?
Yes! Sometimes even warmer.
Natural fibers like merino wool actually provide better insulation, especially when wet. They also regulate temperature more effectively, preventing overheating during activity.
While synthetics can be warm, they often don’t match the adaptability of natural fibers across different conditions.
What’s the difference between organic and recycled materials in base layers?
Organic materials (cotton, wool, hemp) are grown without pesticides and processed without harmful chemicals. They’re biodegradable and support sustainable agriculture.
Recycled materials reduce waste and energy consumption but still have some environmental impact through microplastic shedding and non-biodegradability.
Can I use sustainable base layers for high-intensity activities like running or cycling?
Absolutely! Modern sustainable base layers are designed for performance:
- Merino wool naturally wicks moisture during intense exercise.
- Natural fibers provide excellent ventilation.
- Odor resistance is particularly beneficial for high-intensity activities.
- They maintain warmth even when damp from sweat.
This has been your comprehensive guide to the best sustainable base layers & thermals for winter.
Your base layers are the unsung heroes of your winter wardrobe. They’re the foundation of your cold-weather comfort, quietly keeping you warm and dry.
So why not upgrade your winter wear with a sustainable style this year? By choosing eco-friendly base layers, you’re not only investing in your own comfort but also contributing to a healthier planet.
Embrace the warmth and feel-good factor of sustainable fashion. Layer up, stay warm, and make a difference!
