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Is Merino Wool Better than Synthetic? Backpacking FAQ

Is Merino Wool Better than Synthetic? Backpacking FAQ

Choosing the right type of clothing is vital when preparing for any time in the great outdoors, particularly when it involves activities like hiking and backpacking. Having the wrong gear can make or break your experience – being cold or wet in the outdoors is far from enjoyable.

Your base layer is one of the key items for keeping your body temperature well balanced and free of moisture or sweat. However, choosing the right base layer can be a difficult decision, with so many choices available. There is a lively debate around whether merino wool or synthetic fibers are the better fabric to be wearing out on the trails and knowing which to choose for your next adventure is more complicated than you might think.

So, is merino wool better than synthetic as a backpacking base layer? In many circumstances the answer is yes. Merino wool is an incredible natural fiber that is breathable, quick drying, odor resistant and soft to touch. Of course, the reality is always more complex, and there are still some elements that synthetic fibers do better, such as being even quicker to dry and its durability over time. However, when it comes down to a choice, merino wool is generally a consistently high performing and more all-round good option for varying hiking and backpacking adventures.

What exactly is merino wool?

Merino wool is a natural fiber that is less than 24 microns in diameter and one of the finest you can find in nature. This makes it very different from traditional wool, which is heavier, bulkier and also, itchier when next to skin.

Merino also trumps other natural fibers like cotton for hiking and backpacking purposes, because of its ability to insulate your body and dry quickly. Cotton, on the other hand, can absorb up to 20 times its weight in water, making it unsuitable for sweat-inducing activities – unless you want to appear as though you’ve just had a fully clothed shower after a strenuous hike.

Merino wool is also unique in that the particular sheep that grow the wool also produce lanolin, a natural anti-bacterial, which in turn makes the fabric odor resistant. This is perfect for when you’re sweating it out on the trail with other people – no one wants to be the one with terrible body odor.

What is synthetic wool made of?

Synthetic fibers are derived from chemicals rather than nature like merino wool. Synthetic clothing is usually made from polyester, often blended with other artificial fibers like spandex, elastane, nylon or polypropylene in order to give desirable effects such as flexibility, durability or softness.

Why you need a good base layer fabric:

Before you consider whether merino or synthetic clothing is better, it’s first important to understand the very purpose of a base layer for hiking and backpacking.

It’s become almost accepted philosophy among the hiking community that wearing layers is the best way to go for dressing for the outdoors. The idea is that your base layer, or also known as next to skin layer, should be moisture wicking in order to remove the sweat from your body and keep you dry.

A mid-layer should then be insulating, adding warmth, while your outer layer is for weatherproofing and keeping your body safe from the elements, if needed.

In this sense then, the base layer’s job is to balance your body’s temperature, as well as be comfortable to wear as it is ultimately against your skin. Considering this, when choosing a base layer option for your next hike, and against which I’ll compare merino and synthetic wool, the ideal attributes a good base layer should have are:

  • Warmth
  • Comfort
  • Moisture wicking
  • Odor resistant
  • Durability
  • Price

Staying dry and warm with merino wool base layers.

Merino wool vs synthetic as a base layer:


It’s difficult to compare the warmth of synthetic and merino garments, as this generally depends on the thickness and fit of the fabric as well as what it’s made from.

The best thing about merino is that it comes in varying ratings and you can choose depending on the climate and what kind of warmth you’ll need. Generally, merino clothing comes in weights measured in GSM or grams per square meter. Ratings of around 150 GSM are considered optimal for warmer temperatures as they are thinner, while 250 GSM is perfect for cooler temperatures.

Synthetic fibers, on the other hand, also come in varying thicknesses. However, without a standard weighted rating like merino it can be difficult to determine how warm something made from synthetic would be, other than simply judging by the feel of the material.

When it comes to being insulated and keeping you warm even when wet, merino certainly beats synthetic fibers as well.

It has the ability to absorb up to 30% of its weight in water without losing its insulating affect, leaving you feeling dry and warm throughout a a long day on the trails.


In terms of comfort, it can be a personal preference or tolerance when deciding on materials to wear. It’s important to consider whether a fabric will be itchy or lead to chafing, which are common irritations while hiking, especially with a heavy pack.

Many people assume that anything made from wool is likely to be itchy to the skin, however, merino is certainly not. Its ultra-fine fibers make it soft and light, as well as breathable – three important things you want while moving your body.

Synthetic materials like polyester can certainly be made to feel soft and comfortable, however, it’s in the wet when synthetic becomes a little less comfortable. Polyester doesn’t have any capacity to hold water, which is fine in dealing with sweat but in the rain, this can make it feel rather clammy against the skin. Merino, on the other hand, can absorb some of the moisture making it still feel soft even when wet.


A fibers’ moisture-wicking ability is one of the most important factors, as a base layer’s primary purpose is to keep you dry. Merino wool can absorb up to 30% of its weight in water, which means it can soak up your sweat and allow the moisture to be evaporated without you feeling wet. In saying that, even when it does soak up weight in water, it retains its insulating effect and won’t leave you feeling cold after you stop moving.

On the other hand, synthetic materials tend to be hydrophobic, meaning they don’t absorb water. This makes them dry extremely fast – even faster than merino wool. In fact, when you sweat while wearing synthetic clothing, it moves the moisture to the outside where it can evaporate – so in affect, doing a similar job to merino wool just in a different way.

However, when synthetic clothing does get wet, like in heavy rain, for example, it tends to be less insulating than merino wool and more uncomfortable if you’re on the move.

Odor resistant

This is a case of, you have to wear it to believe it. Merino wool is naturally odor resistant, since the sheep that produce it also produce lanolin which prevents smelly bacteria from sticking to the fibers. Most people don’t quite believe that a piece of clothing can remain smell-free after hiking for hours in tough terrain or hot conditions, but merino wool certainly can.

In fact, for any sort of multi-day hiking adventures, merino wool is the ultimate fabric because you don’t have to wash it very much. It’s moisture-wicking and odor resistant features literally means you can somehow wear it day after day, hike after hike, and it still smells relatively acceptable – trust me, I’ve tried it.

Synthetic materials, on the other hand, do not possess this magical ability. However, some brands are now making synthetic base layers with antimicrobial agents, so they are also odor resistant to a point, although this usually fades after a few washes.


In terms of durability, this is where synthetic materials tend to trump merino wool. Most agree that they last much longer and can be washed simply without having to worry about any care instructions.

The fine merino wool, however, is rather delicate and over time, the clothing tends to thin out or puncture with holes. There are some ways to avoid this though, such as following the care instructions and simply washing less – it is odor resistant after all.


The money factor can also come into play when you’re deciding on purchasing new clothing. This is always difficult to compare as it widely depends on brand and quality. However, as a general rule, merino wool is more expensive than synthetic fibers.

The quality of the wool and also whether an item is made from 100% merino as compared to a wool blend affects the price of garments, but in most cases, you’ll find synthetic garments are generally cheaper.


Product Recommendations

If you’re deciding to invest in merino wool, then Icebreaker and Smartwool are considered two of the best quality merino wool garment makers in the outdoor industry. Their products are usually made from 100% merino wool and they both offer varying weights from 150 up to 260 GSM – meaning you can purchase depending on the kind of climate you need it for.

If synthetic materials still appeal to you, then Patagonia’s Capilene range of polyester base layers are regularly included in round up base layer lists. They also offer a merino and synthetic blend in their Capilene range, so you can get the best of both fibers.

Proving that merino is becoming more of a favored choice, other brands such as Arc’teryx also produce a merino and synthetic blend base layer called Satoro, for all round backcountry adventures.

In conclusion…

So, as you can probably appreciate, choosing between merino wool and synthetic garments for your next outdoor adventure can be a difficult decision. However, in most circumstances, you can’t go wrong with merino wool products; as they effectively remove moisture from your body, keep you warm even when wet, remain odor free and are breathable and comfortable to wear.

To varying degrees, synthetic fibers like polyester can have many of these elements too, it’s just merino often does it better and more consistently.

In saying that, some people still prefer to have synthetic garments for warmer temperatures as they do dry quicker and are also more durable and cheaper to buy. However, if these factors are important to you then you can always opt for a merino and synthetic blend – of which there are more and more products available all the time.

Happy hiking!


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