Pick a Sleeping Bag

Sleeping Bags: Synthetic Insulation vs. Down Insulation 


Next to your tent, your sleeping bag is one of the most important purchases you'll make for camping and backpacking.   And the biggest decision is whether to buy a sleeping bag with synthetic insulation or down insulation.

First, determine what your needs are and how you plan to use your bag.  As a rule of thumb, down sleeping bags are warmer than synthetic - but synthetic bags retain more warmth when they get wet.  So if you're planning to use your bag for extended canoe or kayak trips - stop reading and buy the best synthetic bag.  If you're planning a big wall climbing trip where a storm can trap you on the rock, and warmth can be a life-or-death factor - buy a synthetic bag!  For the rest of us there are other considerations.

Down Insulation:

Down comes from the layer of fine feathers found beneath the tougher exterior feathers.  Goose down is the most common source of down but other sources can include ducks and chickens.  In the US, any product labeled "100% Down" must contain all down feathers.  A product labeled "Goose Down" must contain a minimum of 90% down feathers (the rest are regular feathers).  Products labeled simply "Down" can contain a mixture of fibers, down, and other feathers.

Down quality - known as Fill Power - is measured by the number of cubic inches displaced by one ounce of down.  The highest quality of down comes from Eider ducks, common in Scandinavian countries, with a fill power of 1200.  The fill power of most down products ranges from 400 - 900.  A fill power of 550 will still keep you warm but if you're a minimalist counting the smallest number of ounces to carry, a high fill power will mean more warmth with less weight.

A three-season down sleeping bag should have a fill power rating of about 600.  A true four-season bag designed for sub-zero weather should have a fill power rating of 900 - 1000.

Advantages of down sleeping bags:

1. More warmth for the weight and easier to compress.

2. Usually more durable than synthetic insulation.

Disadvantages of down sleeping bags:

1. Wet, untreated down loses much of its insulative properties.  (Treated down such as DownTek and DriDown stay hydrophobic longer.)

2. Down bags cost more than synthetic bags, generally about 50-100% higher for same temperature rating.

 Synthetic Insulation

So now we know down is warm but, unless it’s treated, doesn’t do well in wet or humid conditions. Enter synthetic insulation. Synthetic insulation is designed to replicate the qualities of down, but retain them even when wet. It’s made with polyester fibers that are arranged in different sized filaments and intertwined, mimicking down’s lofty clusters. These ultrafine fibers trap warmth in air pockets, providing great warmth… though not quite as good as down. In addition, synthetic insulation has a slightly higher weight-to-warmth ratio than down, meaning it needs to be heavier to achieve the same warmth as down.

The upside to synthetic insulation is that it is much more resistant to moisture, and when it does get wet it dries faster; Synthetic insulation can often dry within a day—maybe even hours—if put in the sun or on a windy day. Synthetic insulation also tends to be friendly on the wallet and is naturally hypoallergenic.

Advantages of synthetic sleeping bags:

1. Lower overall price.

2. Maintains thermal properties when wet.

3. Does not reduce loft in high-humidity/ sweaty sleeping conditions.

4. Easier to clean.

Disadvantages of synthetic sleeping bags:

1, The loft does not last as long as down (3-5yrs vs 8-10yrs)

2. Does not compress as small as down.

3. Higher weight to loft ratio. (Compared to 650+ down fill)

4. Retains smells more than down. 


Down can be harvested in a variety of ways. Some birds are killed for their down and meat, while others are killed solely for their down. Some birds, geese in particular, are live plucked of their breast feathers. Others, such as the eider duck, line their nests with down, making harvest a pain free process. Animal rights activists consider live-plucking to be a cruel and painful process, especially because it happens regularly. Some companies do not use down from live-plucked geese or down harvested from animals that were force-fed in order to produce foie gras. Some of the smallest premium companies source the highest down from geese that aren't live-plucked or force fed; they collect naturally shed down from molting. Some vegans might consider avoiding down products or purchase them from a company that guarantees no harm to animals.