Down vs Synthetic Sleeping Bags


When purchasing a sleeping bag look for a bag which will keep you warm in the coldest temperatures you might encounter with that particular sleeping bag. If you camp both during the summer and the winter you should consider owning two sleeping bags.  Click on the video below to learn more.

When deciding on a temperature rating for your sleeping bag, keep these ideas in mind:

It’s a good idea to plan for temperatures slightly colder than you expect.

How warm do you sleep? Do you sleep “warm” or “cold”? If you sleep “warm”, figure it gives you a margin for error. If you sleep “cold”, purchase a bag rated for 5-10ºF below the lowest temperatures you will encounter.

Keep in mind that what you eat can affect how “warm” you sleep. Things which are hard to digest, such as meat, will cool you off, while fatty foods will help keep you warm. Staying well hydrated can also help your body stay warm at night.

What clothing you wear while sleeping can affect temperature rating as well. Plan to sleep wearing a minimum of clothing such as a thin synthetic long-underwear layer. Add dry non-cotton clothing such as a down vest of fleece jacket for added warmth. Too much additional clothing can compress loft and decrease the efficiency of your bag.

Construction techniques such as hood shapes,longitudinal baffles, multi-baffled foot sections, and draft tube designs can affect sleeping bag warmth. Make sure there are no areas which will be flattened out during use and create cold spots.

Your sleeping pad can have a huge influence on your sleeping comfort both in terms of cushioning and in terms of warmth. Make sure that your pad insulates well enough for the conditions you will encounter.

The fill power rating for down is an indication of the ability of the down used to “loft”. The number given is the amount of volume one ounce of down with fill in cubic inches, (ie. One ounce of 775 fill power down will loft to 775 cubic inches). 600 fill-power down is quite adequate for most applications. Those wanting “The Best” will find the 750 and 775 fill power down bags to be well worth their extra price. In addition to being lighter and more compressible for the same warmth rating, higher quality down will retain its loft longer.

When choosing between down and synthetic sleeping bags keep these points in mind:

Down sleeping bags offer reduced weight and stuffed size. A down sleeping bag can weigh up to 25% less and compress 25% or more smaller then a synthetic filled bag of the same temperature rating.

Comfort and durability are two other reasons to choose a down bag. Down bags have a wider temperature comfort range, meaning that you can probably use your 0ºF sleeping bag in temperatures up to 30-40ºF and not be too hot. Down bags also hold their “loft”, or insulating ability, quite well over time. Synthetic sleeping bag fills tend to have a narrower comfort range and can lose a considerable amount of their insulating ability in just the first 30-60 days of use. This means that a synthetic filled sleeping bag rated at 0ºF when new may only keep you warm down to 20ºF after a couple of seasons. For this reason it is a good idea to replace your synthetic sleeping bag more frequently if you are counting on it in cold conditions.

Synthetic sleeping bags offer great performance in wet environments. A wet down sleeping bag has very little insulating value. Therefore, when using a down sleeping bag, you must practice good moisture management, keeping your bag dry at all times. Synthetic filled sleeping bags retain much of their insulating value when wet and are a good choice for those wet and wild trips!

Price can be the final determining factor. Down bags cost 30-50% more than synthetic bags. A top-quality down bag can be over twice the price of a comparably rated synthetic filled bag.

All things considered, we recommend down bags to most of our customers, however your personal requirements for warmth, weight, stuff-ability, comfort range, and price will make the final determination.

Marmot Mountain Works