Addnature Online Shop - addnature
Addnature is temporarily redirecting its UK customers to our partners in adventure,
Telt Guide

Down vs Synthetics vs Wool

Keeping warm is the key to success when it comes to enjoying a happy, active outdoor lifestyle. Everything is more fun when you’re not frozen stiff and you’ll know exactly when you need more than just a fleece to keep warm. This guide will help you find something perfectly suited to your needs.

The basic principle is the same for every piece of insulating clothing, whether it’s a jacket, pair of gloves or sleeping bag. Small spaces in the fibres trap body heat in order to keep you warm when it’s cold. The bigger the air barrier between the body and the cold, the more efficient the insulation is.

Insulation is mainly made using down or synthetics, but even wool is becoming common nowadays and you’ll find a variety of hybrid jackets that strategically use different kinds of insulation exactly where you need them the most. Every kind of insulation has its advantages and disadvantages. That’s why it’s important to choose the right type depending on your chosen activity and weather.

Insulation Advantages Disadvantages Best suited for…
  • Lightweight
  • Compressible
  • Quickly regains its shape
  • Long life
  • Best insulating ability in comparison to light weight
  • Sensitive to wet
  • Dries slowly
  • More expensive
Activities with lower intensity when you don’t sweat as much an in everyday life. Excellent in cold and dry weather.
  • Insulates even if it gets wet
  • Lower price
  • Keeps its shape
  • Heavier than down
  • Occupies more space than down
  • Not as good insulating abilities in relation to weight as down
High intensity activities when you sweat or in wet or damp conditions.
  • Insulates even if it gets wet
  • A natural alternative to synthetic
  • Odour resistant
  • Heavy
  • Not as compressible
Long and intense wear in varying temperatures.


Down insulation can be found in everything from sleeping bags to winter parkas and compressible “puffy” thinner pieces that you can keep in your rucksack. Down is ultra-light, ultra-compressible and ultra-warm. It’s approximately three times as heat efficient in comparison to weight as synthetic insulation. To put it simply, choose the warmest and lightest when the weather is cold and dry. Down insulation is also very durable and has a long life.

Down insulation’s Achilles heel are wet and damp conditions since it loses its loft and insulation abilities when it gets wet. Often high humidity is enough to get it wet and it dries slowly. Much of the down used in premium class products is treated to resist better against wet, but it still doesn’t resist as much as synthetic does.

Give your down clothes the care they deserve (and that doesn’t include keeping them stuffed in a small bag in the back of your closet!). Hang them up after using them so that the down doesn’t lump up and leave cold spots.


Synthetic insulation is reliable when the weather is wet. It resists moisture better and maintains its insulating abilities even when the fabric does get wet. This makes synthetic insulation ideal for rainy days, high humidity or for high intensity activities. You’ll avoid the jacket turning into a heavy lump of ice when temperature drops. Synthetic is also an excellent choice for ice climbing since the lining stays in place even if you happen to rip your jacket.

When you pick synthetic insulation for jackets, a good idea is to think about the amount of insulation it has. In general a jacket with 50-100 g/m² of insulation is best suited for spring and autumn or as a reinforcement jacket during winter. 100-200 g/m² warms in really cold conditions. As always there are some exceptions – wherein new ways of constructing the garments make the synthetic insulation both lighter and warmer.


Recently wool has been breaking ground in the world of insulation. Wool is light, warm, resists moisture without losing its insulating abilities and regulates body temperature. It’s the natural alternative to synthetic. On top of that wool has other natural qualities, such as being odour suppressing, that make this type of insulation something else. We predict a bright future.


Many manufacturers have started using the best of both worlds, creating products by combining down with synthetics. Areas in a jacket that are especially exposed to wet, such as shoulders and collar, are made with synthetic while the torso gets down in areas where warmth is needed the most. Whilst wearing hybrids offers many advantages, the combination becomes somewhat heavier than down and somewhat less water resistant than synthetic.


What is fill power?

Fill power is an indicator of the down’s quality and tells us how much volume a given weight of down fills. They higher the figure, the better the insulation. A lower figure needs more down to reach the same heating capacity, which results in a heavier piece of clothing. A higher figure means it’s compressible to a lesser extent.

Is down always warmer than synthetic?

No. Fill power, as described above, determines the quality of down and there are many different kinds of synthetic materials that have reached far in copying the down’s qualities. Some synthetic insulations are today so efficient that they are equivalent to relatively high quality down. The price often reveals the difference. A cheaper down jacket often has simpler down insulation - a more expensive synthetic jacket can be both lighter and warmer.

Is it just the lining that determines how well an insulated piece of clothing is?

You’d think so. There’s a lot of talk about fill power, synthetic that copies down and wool that doesn’t smell bad. However, the truth is that many other factors are also important. A windproof piece of clothing will of course trap more heat than a ventilating one. A waterproof piece of clothing can even be too dense, overheating you and making you sweat, which is never good in cold weather. That is why we keep emphasising the importance of choosing the right product according to activity. Other things to keep in mind are how much of your body’s surface the piece of clothing covers and if it protects extra sensitive parts of your body.

Why should clothes ventilate?

Clothes will simply get too hot without ventilation. You’ll start sweating and get cold! Ventilation is your saviour.

I have seen it says 85/15 in the specifications of the down, what does it mean?

Down isn’t just any feather. Down feathers are the small, fluffy feathers that lie closest to the bird’s skin. The numbers tells us how much of the filling consists of down and how much is ‘standard’ feather. The higher the number of down feathers, the better the insulation is. 85/15 means you get 85 grams of down per 100 grams of filling.

Do I have to choose, can’t I just buy water resistant down?

The water resistant treatment makes the down resist wet better, without having a negative effect on the down’s insulating ability. It still doesn’t insulate as well when it’s wet as wet synthetics do.

Should the down be washed together with tennis balls?

No, tennis balls risk damaging the down. Pay attention to the washing advice for your specific piece of clothing. If you still insist on using tennis balls, then choose ones without print.