Choosing the Right Sleeping Bag

Choosing a sleeping bag

A good sleeping bag is the most valuable piece of camping gear you can own. Sleeping bags are designed to keep you from feeling cold, yet the purpose of a sleeping bag isn't really to warm you; it's to help maintain your inner body temperature. There are many styles and varieties of sleeping bags available for camping and hiking. This article is designed to help you find the sleeping bag that will best suit your needs, whether you're taking long backpacking trips or simply pitching a tent in the back yard.

Before choosing a sleeping bag there are a number of questions you need to ask yourself. What is your budget? A sleeping bag depending on the temperature rating and materials it is made from can cost fifty dollars to several hundreds of dollars. What kind of camping will I be doing? Will you be car camping, camping at a primitive site, or hiking in the backcountry? If you are car camping the need for a lightweight and very compactable down sleeping bag is not as important as if you were backpacking in the backcountry. What kind of weather will you be camping in? Is where you plan to do most of your camping going to be in arid conditions or are they damp and wet conditions? If you are camping in a dry climate you most likely will not need the added expense of a completely waterproof sleeping bag. What is the coldest temperature that you will be sleeping in? Unlike other gear like boots and tents that can do double duty, you may have to consider buying different bags for different conditions.

Temperature Ratings
Most of the time, manufacturers will give their sleeping bags a comfort temperature rating - this being the lowest temperature at which the average person will still be able to have a good night's sleep while using the bag. This gives a good indication of performance, but cannot be taken as absolute. At the present, there is no standard or universal method for determining ratings. This means that manufacturers are free to make their own claims about their bags' warmth.

I recommend adding 10 degrees to the temperature rating on a sleeping bag for a more realistic picture of its ability to keep you warm. For example, a bag rated for 30°F should only be used in temperatures that never drop below 40°F. On the other hand you would not be comfortable in a 10° bag when it's a 70° night. People in warmer climates should buy bags with higher temperature ratings.

down mummy sleeping bag Down Mummy Sleeping Bag

EN Ratings
A new standardized rating system has been widely adopted in Europe, called EN 13537. Some U.S. bag makers like Marmot have also adopted the system (and others are planning to). The system assigns bags a series of ratings:

  • Upper limit = the highest air temperature at which the average man can sleep comfortably.

  • Comfort = the lowest air temperature at which the average woman can sleep comfortably.

  • Lower limit = the lowest air temp at which the average man can sleep comfortably.

  • The ratings are established after a set of standardized tests using a mannequin that has a number of heat sensors.

Insulation Materials- Down versus Synthetic

Down is the lightest,most efficient insulation you can get. It's also the most compressible (a big plus for backpackers). Down is generally more expensive than synthetic, but it also depends on the fill-power, which is a way of rating the quality of down. Fill-power ratings range from about 500 to 900 cubic inches per ounce. The figure refers to the number of cubic inches one ounce of down will fill. Since the warmest down is the loftiest down, the higher the number the warmer you're going to be.

There are many different types of synthetic insulation, but it is generally fluffy polyester fibers that do not absorb water, making it a smart choice for any camper who might be faced with wet conditions. Although synthetic bags are typically bulkier and heavier, they are less expensive.

Types of SleepingBags

rectangular sleeping bag Rectangular Sleeping Bag

The rectangular bag is usually inexpensive and the typical family sleeping bag. Versatile and roomy, the rectangular bag is similar to aquilted blanket, allowing you to toss and turn as you would at home and you can even zip two bags together for extra space. Contrarily, these bags promote heat loss, making them best suited for warm weather camping. They are also the most bulky which makes them a poor choice for backpacking.

The mummy bag is designed to prevent heat loss while you sleep. The tapered, cocoon shape means your body heat doesn't travel, helps to keep you warm. Mummy bags are tight around the feet and come with a hood to prevent heat from escaping through your head. Both features are vital during cold weather camping. Because mummy bags use less space, they are easy to compress and pack away. Their light-weight design makes them a good choice for backpacking, cold nights and high altitudes.

For those who don't like the confinement of a mummy bag but still require more warmth than the standard rectangular bag, semi-rectangular bags make a good compromise. Narrow at the feet, but roomy around the shoulders, arms and hips, barrel bags ensure you can move and not feel restrained. This freedom of movement means these bags are not as warm as mummy bags or as light weight.

Women's Bags
Women's sleeping bags are narrower at the shoulder and wider at the hip than unisex sleeping bags, to prevent too much air circulation. Women's sleeping bags may come in various sizes (i.e., short, regular or long) to fit all heights. Also, women's bags usually offer extra insulation at women's "cold spots," namely the foot box and torso. Women tend to produce less heat than men, so they may need a sleeping bag with a lower temperature rating than men for use in the same conditions.

Bag Construction

Better quality sleeping bags outer shells are usually made of nylon because of its lightweight durability. Nylon bags can be either silky nylon taffeta or slightly more durable rip stop nylon, which has extra-sturdy threads woven into the fabric in a cross hatch pattern making it not as smooth as nylon taffeta. Some nylon shells utilize a very thin, highly breathable laminate like Gore-Tex which may come in handy if you are camping in a wet environment. However they also are more expensive.

Less-expensive bags may be constructed of polyester instead of nylon, which is fine if you are an infrequent camper and won't put lots of miles on the bag. The lining of sleeping bags is usually smooth nylon or polyester.

Other Construction Features to Consider

Anti-snag 2 Way Zipper - To prevent the 2-way zippers from snagging the draft tube or the bag edges, an "anti-snag strip" of webbing is sewn in behind the zip.
Draft Collar - Tubes of insulation inside the hood on mummy bags that seal the neck and shoulders from heat loss.
Draft Tube - A zip baffle runs the full length of the bag, behind the zip, to prevent heat escaping through the zipper.
Trapezoidal Foot Box - Provides extra foot room.
Blanket or Single Layer Quilted Construction - A method in which the shell and liner are sewn together to keep the insulation in place. This method is not as warm as the following two construction methods.
Double Layer Offset Construction - A method where insulation is sewn to the shell and liner separately with stitches offset to improve insulation efficiency, loft and warmth per pound of insulation.
Shingled Construction - A method where insulation is stacked in layers and sewn to the shell and liner, similar to using the insulation as its own "baffle".

When looking for a sleeping bag to buy you need to consider several key areas. I hope that the information above will give you some insight to what kind of sleeping bag will best fit your needs.

For more information check out our Sleeping Bag Buying Guide or click here for more information on Choosing a Sleeping Pad.

-The Gear Doc
Andy Hawbaker
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Andy Hawbaker
Andy is a hiker, backpacker, snowboarder and outdoor fanatic. When he isn't exploring the Rocky Mountains, burning marshmallows or scratching his dog behind the ear, he shares his experiences here on the Sierra Trading Post Blog.
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