Sleeping Bags : A Quick and Dirty Overview

Another quick and dirty article about a key piece of backpacking and camping gear: sleeping bags

As with previous gear articles, it does not go over specific brands and models, but rather provides a high level overview of what may work for you depending upon your needs,  time of the year, he type of backpacking or camping is done and other factors. This is a meat and potatoes article without a lot of technical jargon. 🙂  Updated for 2013.


As with all gear, there is no ‘best’ option…only what is best for your needs, style, time of year, budget, etc.

Here is a higher level overview that will help pick out the appropriate bag for your needs.

Bag Types

There are three basic bag types: Rectangular, Mummy and a half-way solution called Semi-Rectangular

Rectangular Bags

Rectangular bags are the roomiest of the bags…but also the bulkiest, least heat efficient and tend to be the heaviest of the sleeping bag types.


Coleman Exponent Rectangular Sleeping Bag


Rectangular bags, because they are boxier,  aren’t so much colder..but they DO  take longer to warm up. And they  tend to lose heat if they can’t be cinched up.  They are not as  efficient overall.

You don’t see many (any?) true winter bags in rectangular form.

These bags seem to work best for base camping and/or people who like a lot of room in their bags esp during warmer weather.  They may work OK for colder weather if a balaclava or similar is worn while sleeping. Down hoods can also be bought to extend the range of the bag’s temperature.  These bags can open up to form a quilt, making them a good choice for cooler-warm temps when camping.   These bags also mate up easily to form one large bag suitable for couples use vs the other bags.


Mummy Bag

Mummy bags tend to be lighter, more heat efficient (less room to fill up =  warms up more quickly) than other bags and the choice of many people going longer distances and/or  camping in cold weather.  The hood cinches up really tight for even more thermal efficiency.


Western Mountainering Ultralite


The disadvantage of a mummy bag is that this  bag type is constrictive and may not be as comfortable for some campers.


A hybrid solution is also available.  Semi-rectangular bags offer more roominess than a mummy bag, but more thermal efficiency than a rectangular bag. Many high end manufacturers such as Western Mountaineering and Feathered Friends make  semi-rectangular bags  that are excellent quality and address the needs of people who do not want a mummy bag. Mainly comfort and roominess where weight and bulk is not the primary concern. The roominess tends to come from an extended toe box, chest and head area.


Western Mountaineering Sequoia MF Semi-Rectangular Bag


Semi-rectangular bags do not cinch up as well around the head and, due to having more volume, are not as efficient as a mummy bag in terms of warmth.  Though cold weather bags are made for deep winter camping, the thermal efficiency of the mummy bag may be more desirable. The semi-rectangular bags are the choice of many three-season or so backpackers who want a a little more comfort and don’t mind a weight penalty.

Quilts – Another choice

A choice becoming more popular among both the lightweight backpacking and the hammock camping communities, the quilts are known for their lightness and compressibility in a warm package.


The quilts are also noted for their versatility. Their weights savings comes from a lack of zippers and no bottom section.

Ray Jadine gives an even handed explanation of why quilts may be a good option. 

For cold weather camping, some companies are now making cold weather versions of their quilts.

I used one exclusively this past summer (2012) and have been very pleased with the results. They do take some getting used to, but overall make a good system esp if use with the appropriate clothing (balaclava for example).

Poncho Liner – warm weather dirt bagging par excellence!

A modern granddaddy (or maybe beloved uncle?) of the sleeping quilt above, the poncho liner has been used by many people for down to about 50F (and extended with a poncho and a hat, long underwear, etc.) for a less expensive and/or a minimalist alternate for a sleeping bag.  They are not that light considering their warmth, but do pack down small and are versatile.


Their versatility, price (~$20 at a surplus store) and packability make them a choice for many people to have stashed in a vehicle, camping kit or just  active out in warmer temps and want to take something simple.   A ground cloth, a sun shade, a wrap on  a cold evening around camp, etc. are just some of the uses besides a sleeping bag alternate.

I would not want to use for much past summer or maybe Spring conditions in lower elevations, but it is a good piece of gear to have handy for some situations.  Hammock campers have used them as an underquilt as well.

Down vs Synthetic Fill in Sleeping Bags                                                    

When it comes to fill of sleeping bags (or quilts), the choices are Down or Synthetic (Thinsulate, Primaloft, etc. etc. etc!)

Down – made from, well, the down of geese.  Comes in various fill powers. Generally, the higher the fill power, the better and warmer a bag or garment will be.  Budget bags come in 550-650 fill whereas high-quality bags generally come in 750+ fill.


Cute geese. Where down comes from!  

Advantages of Down

  • Down is ounce for ounce still the warmest insulation you can get in sleeping bags, jackets, mittens, etc.
  • A well cared for down bag will last for many years (if not indefinitely; depends on the use).
  • A down bag is more breathable than synthetics and is therefore more versatile in different conditions.
  • Finally, down will compress better than synthetic filled garments.

Disadvantages of Down

  • A down sleeping bag is usually more expensive than a comparable synthetic bag [1]
  • Expensive to clean vs a synthetic. You can’t just pop it in a washer. A down bag should be hand washed or brought to a professional cleaner.
  • Lastly, down is useless when wet. When a down bag becomes wet, it loses loft  and insulation. It will no longer function. Care must be taken to not make sure the down bag does not become wet.

[1] Though, I am a big fan of Campmor’s Down Bags for the budget minded backpacker or camper The 20F bag appears out of stock as of this writing. Kelty also makes a budget-minded down bag that has received good reviews.

Synthetic Fill

Synthetic fill is modern insulation called by brand names such as Thinsulate and Primaloft.  The synthetics loft up and trap air particles in between the fibers (much like down).


  .  Slight exaggeration of the chemist who designs synthetics fill

Advantages of Synthetics

  • Warm when wet. The fibers do not collapse like down so the insulation will still provide warmth (not that any wet bag would be comfortable!)
  • Usually less expensive than a comparable down bag
  • Easier to care for. Can be put in a standard non-agitating washer

Disadvantages of Synthetics

  • Bulkier and heavier than a down bag
  • Longevity is not as long. All the stuffing and un-stuffing compresses the fibers more than a down bag.
  • Not at breathable so not as adaptable in variable conditions
  • More variable in quality vs their down counterparts. An inexpensive down bag is pretty decent to good.  A budget synthetic bag is usually much heavier, bulkier and of lesser quality than a higher end synthetic bag


So which is best? It all depends!  As my friend Garlic put it once: “Down is always better..except when synthetic is better”. 🙂

If I had children outgrowing their gear, was a person who is not careful with their bag in wet weather, not sure if I wanted to get into backpacking or on a very small budget, I’d go with the synthetics.

However, if you are an avid backpacker or camper, I think you are better off with down. A down bag is an investment and is less expensive than a synthetic bag in the long term.

In my many thousands of miles of backpacking, I never have had an issue with a wet down bag. That includes trips on the Appalachian Trail, the Benton MacKaye Trail and who many trips all over New England where it is much wetter than my current home in the Rockies. A garbage bag placed in my pack with a trash compactor bag does wonders! 🙂

On the other hand, since I don’t do enough deep winter camping to justify a high end down bag, my -20F bag is a synthetic. Likewise, the sleeping bags that someone and I use for shoulder season or winter car camping are synthetic semi-rectangular bags rated to -15F (with fuzzy fleece lining!).  The -20F winter bag is a true winter backpacking bag (if somewhat heavy and bulky).  The semi-rectangular bags are definitely for the base camp and NOT for backpacking.

Final Thoughts

  • Whichever bag type or insulation you use, DO NOT stick your head completely inside the bag. You’ll want to make sure you leave a space open for your mouth and nose at night. Otherwise, the approx one liter of water the average person breathes out at night will collect IN your bag. :O
  • Besides temperature rating and insulation of the bag, the appropriate sleeping pad is necessary for the conditions you are going to be in
  • Long underwear, a hat, dry socks and proper hydration (and having fuel in the stomach) also helps ensure a warm night’s rest
  • Finally, whichever type of bag you use…get out there and use it! We use gear to enjoy the outdoors; we don’t use the outdoors to enjoy gear. Or shouldn’t anyway. 😉
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8 years ago


Thanks for an extremely accessible overview and intro. Excellent.