Down vs Synthetic Sleeping Bags

We are often asked the benefits of down filled vs synthetic sleeping bags. Both types have advantages and disadvantages but, to put it simply, for virtually all of the outdoor activities that our customers are involved in, down is the better choice and this is reflected in our range.

If you look at our entire sleeping bag range, currently 60 models, only 8 have synthetic filling.

For a full explanation of why you would choose some of our sleeping bags over others see our blog Which is the best sleeping bag for you?

So, why is down better than synthetic?


Here are the advantages of down as we see it. Down is one of the most incredible natural fibres in the world. It is incredibly resilient. Treated well, a down sleeping bag will retain its warmth for many, many, years. In many cases the fill will outlive the life of the shell. By comparison synthetic fills compact and lose their loft. From many years of experience with using both types, I would suggest that the life of a down filled sleeping bag is about three times as long as a synthetic.

Warmth to weight ratio

Good quality down offers the best warmth-to-weight ratio of any material that you can get. It offers an even better advantage in warmth to compressibility or packed size ratio. A sleeping bag's weight is also affected by design and shell materials of course, but the filling is the most important factor. Put simply, for a given warmth a down bag will give the smallest, lightest package possible. As most of our customers are carrying the bag whether they are hiking, ski-touring, travelling or cycle-touring, this is a defining factor in the choice of the best sleeping bag for them.

Mont Helium Sleeping Bag

The Mont Helium 450 at only 800 grams and -7°C rating is an example of an extremely small, light and warm sleeping bag.

Advantages of synthetic sleeping bags


Synthetic sleeping bags are much cheaper than their down-filled cousins. However, in the long run they are not necessarily better value (see note above about longevity) and the price saving needs to be balanced against the utility of the bag.

Better when wet

Synthetic fills absorb much less water when wet than down. This means the bag dries much quicker and is in general more resistant to moisture. Field drying a sodden down sleeping bag is an extremely difficult task. It also means the bag is easier to clean and care for. Thus a synthetic bag may be a better option for kayaking or river rafting trips where a catastrophic water soaking event is always a possibility.

Note a considerable number of our down-filled bags are offered in water-resistant shells which helps protect the down from moisture.

See for example the Mont Hydronaute bags such as the Mont Brindabella. The Exped Waterbloc series have not only a water resistant shell but welded seams.

General Camping

A synthetic sleeping bag may be a better option for general camping where weight and size are not a problem. If it is being used around dusty climbing campgrounds for example, it will be easier maintain.

To help you with your sleeping bag selection see our blog on Which is the best sleeping bag for you?

by Neil Blundy