Alpaca Wool GSM Guide:How to Choose the Perfect Weight for Any Adventure

At 5,000 meters above sea level, survival is an art. Alpacas have mastered it for centuries. And now, you can too.

Whether you’re hiking sunlit ridgelines or working from home, the clothes you wear shape how you move, feel, and perform. That’s why GSM—grams per square meter—is more than a number. It’s a guide to freedom, warmth, breathability, and versatility. At Arms of Andes, we offer four alpaca wool weights, each built with a specific purpose, season, and lifestyle in mind.

In this guide, we break down what each GSM level means, what it’s perfect for, and how to build the ultimate layering system from the mountains to your morning routine.

110 Featherweight | Breezy, Barely-There, Built for Movement

Our newest weight, 110 GSM, is the lightest alpaca wool shirt you'll find on the planet. Designed for those who thrive in sun, sweat, and simplicity, it feels like wearing nothing—only better.

Currently available in: 
Tank tops, T-shirts, long sleeve T-shirts and sun hoodies—perfect for travel, summer, or everyday wear.

Best For:

• Day hikes under the sun.
• Travel in hot climates.
• Everyday wear in spring and summer.
• Ultralight adventures when every gram matters.

Avoid If:

• You’re carrying a heavy pack or doing activities with friction (climbing, scrambling).
• You need thermal insulation in cold or windy environments.

Why You’ll Love It:
Featherweight is all about breathability without sacrifice. It wicks moisture fast, dries quickly, and resists odor naturally—thanks to the antibacterial power of 100% Royal Alpaca wool [1,2,3,4]. If you want a shirt that stays clean, fresh, and cool across days of movement, this is it.

“Featherweight with an airy feeling—because you don’t need heavy to feel ready.”

160 Ultralight | The Travel Essential, Base Layer King

This is your ultimate travel companion and base layer go-to. At 160 GSM, Ultralight offers slightly more density than Featherweight, giving you a touch of warmth while keeping everything breathable, sleek, and incredibly soft [2,5].

Made into:
Men's underwear, women's underwear, tank tops, T-shirts, long sleeve shirts, neck gaiters, gloves and beanies—all minimalist travel staples.

Best For:

• Base layer for mountain hikes or cool climates.
• Travel with minimal luggage.
• Everyday wear: office, flights, cafés, casual city use.
• Light hikes with a small backpack.

Avoid If:

• You're mountaineering or doing high-friction activities like bouldering.
• You need insulation as a standalone piece in cold weather.

Why You’ll Love It:
It’s called “The Perfect Travel Shirt” for a reason. It resists odor, folds tiny, dries fast, and keeps you feeling clean even on multi-day trips [2,3,4]. It performs in the Andes, but it looks at home in a dinner party. Seamless fit, zero itch, total style.

“Go farther, pack lighter—and look better doing it.”

300 Lightweight | The Do-It-All Midlayer

When the weather shifts or you gain altitude, the 300 GSM layer becomes your best friend. It’s the bridge between light layers and full insulation, adding warmth without ever making you overheat [5,6].

Crafted into:
Leggings, joggers, hoodies, pullovers, sweaters, gloves, arm sleeve and socks—pieces built for layering or lounging.

Best For:

• Hiking in colder temps.
• Base or mid-layer in alpine conditions.
• Camping, backpacking, cold-weather running.
• Loungewear that still performs.

Avoid If:

• You’re in extreme cold without layering.
• You want something as breathable as a base layer for hot climates.

Why You’ll Love It:
You get warmth without bulk. Breathability without sweat. Style without synthetic layers. This is the most versatile piece for fall, shoulder seasons, and year-round layering. Hoodies, joggers, sweaters—you name it.

“Insulation you’ll actually wear—not just carry.”

420 Midweight | Full Protection for Harsh Conditions

The thickest, warmest option in our lineup. At 420 GSM, this layer is your alpine shield—designed for extreme cold, snow, and wind.

Available in:
Jackets, leggings, sweatpants, beanies, gloves, and socks—your no-compromise cold weather arsenal. 

Best For:

• Winter trekking and alpine hikes.
• High mountain climates and freezing nights.
• Snowshoeing, ice camping, ski layering.
• Ultimate warmth without synthetic shells.

Avoid If:

• You’re in a hot or humid climate.
• You want something for active hiking at low altitudes.

Why You’ll Love It:
It’s wind-resistant, warm, and surprisingly breathable [7]. The cut is fitted, the fiber is natural, and the feeling? Like wearing a blanket of confidence. No plastic. No compromise. Just serious protection that feels luxurious.

“This is not your average wool jacket. This is armor made by nature.”

How to Build Your Layering System with Alpaca Wool

In the outdoors, the right layering system is everything. It’s not about bulk—it’s about strategy. Whether you’re hiking under the sun, camping in the Andes, or braving chilly mornings in town, alpaca wool adapts to your journey.

Here’s how each GSM weight fits into your adventure kit:

Base Layer

Worn next to your skin, this layer manages moisture, keeps you dry, and regulates body temperature.

• 110 Featherweight: For hot climates, sunny day hikes, and travel minimalism. Ultra-breathable, ultra-light. Best for light activity with little abrasion.
• 160 Ultralight: Ideal for active travel, everyday wear, and low-friction hikes. Anti-odor and quick-drying, this is the "wear it for days" layer.
• 300 Lightweight: Heavier shirts, hoodies, and pullovers in this weight can double as a warm base when the temperatures drop.

Mid Layer

Designed to retain heat while allowing your body to breathe. Ideal for layering over a base or under a shell.

• 300 Lightweight: Perfect for layering during cooler treks, alpine mornings, or evenings by the fire. Hoodies, sweaters & pullovers add warmth without bulk.
• 420 Midweight: A high-performance insulating layer for extreme cold. Found in jackets, this wool weight locks in heat and shields against wind.

No plastics. No toxins. Just alpaca. The ultimate outdoor fiber.

*Looking for an “outer layer”?

Alpaca wool is your best ally for base and mid layers—but when nature throws snow, heavy rain, or icy winds your way, you’ll need a weatherproof outer shell. These are typically made with synthetics like polyester or nylon. At Arms of Andes, we encourage you to minimize plastics elsewhere by choosing natural, breathable wool layers for everything underneath.

Still Unsure? Start Here:

Why Choose Alpaca Wool? Nature’s Most Intelligent Fiber

Alpaca wool isn’t just soft—it’s science-backed performance built by evolution. Here’s why it outperforms other materials in any climate:

Exceptional Warmth
Alpaca fibers are semi-hollow, trapping heat without weight. Their natural crimp adds loft, making them ideal for insulating layers in cold environments [1,2,5,7,9].

Breathable & Moisture-Wicking
Unlike synthetic fibers, alpaca lets your skin breathe while keeping sweat away. That’s why our base layers stay dry—even on uphill climbs [1,2,3,4].

Temperature Regulation
In the Andes, days are hot and nights are cold. Alpacas evolved to handle both—and so does their wool. It keeps you warm without overheating [1].

Lightweight & Flexible
You get all the warmth of bulkier materials, but with freedom to move. Whether you’re layering under a shell or stretching at sunrise, it adapts to you [5,8].

Hypoallergenic
Alpaca wool contains no lanolin (a waxy substance found in sheep’s wool), making it naturally hypoallergenic and safe for sensitive skin. That means no itch, no irritation, even with all-day wear [9,10,11,12,13,14].

Antibacterial & Odor-Resistant
Fewer washes, less stink. Perfect for multi-day treks and minimalist wardrobes [2,3,4].