A sleeping bag can protect you from the elements and keep you warm. They could even save your life. There are several considerations when choosing a sleeping bag including temperature rating, fill material, size, and weight. There are many excellent sleeping bags on the market and if you know the basics then you can choose the right sleeping bag.
This is the most important consideration for a sleeping bag. The temperature rating is the manufacturer’s “best guess” as to how warm the bag will be for “average person.” You should not use the sleeping bag when the temperature is colder than the temperature rating. This rating is subjective and can inaccurate depending on the manufacturer. When selecting a bag by temperature rating consider:
- The temperature rating is NOT the comfort rating. If you have a 20° bag you will probably NOT be warm if the outside temperature is 20°. A 20° bag will probably be warm and comfortable if the air temperature is about 27° or higher.
- If you sleep cold then select a bag with a lower temperature rating. For example, if the temperature will drop to 30° and you sleep cold then consider a 20° bag. If you sleep hot then you might only need a 30° bag.
- Women tend to sleep about 8° colder than men. Women’s bags normally take this into account and a 30° women’s bag will be warmer than a 30° universal bag. Women purchasing a universal fit bag should take this into account when selecting the temperature rating.
Do NOT purchase a sleeping bag that is far warmer than the outside temperature. For example, if you camping where the night air will be 40° then you may be uncomfortably warm if you use a -20° bag. If your sleeping bag is not warm enough then you can add a bag liner or warm thermals. Each of these can potentially add up to 15° of warmth to the bag.
Sleeping bags come in two styles, namely rectangle and mummy. Backpackers generally prefer mummy bags and outfitters and hunters who sleep in a base camp generally prefer rectangle bags. Mummy bags are lighter and can compress to a smaller size than equivalent rectangle bags. You can get rectangle bags heavy canvas exterior and/or flannel or other soft, comfortable interior.
If you want to create a double bag then it is best to use two rectangle bags. You can create a double bag with mummy bags but you need the same type of bag with the same style/size zippers and you will need to have one right- and one left-handed bag. Right/Left-handed indicates which side has the main zipper. When creating a double rectangle bag just unzip both bags, place then on top of one another with the interiors together, align the zippers, and zip.
Rectangle: Heavier due to more material
Rectangle: More room
Mummy: Less room
- Compressed Size:
Rectangle: Variety including lightweight interior/exterior, canvas exterior, cloth interior
Mummy: Normally lightweight material only
- Double: That is, the ability to zip two bags together to form a double bag.
Rectangle: Very easy
Mummy: Can be difficult
Anatomy of a Sleeping Bag
These are the basic components of a sleeping bag.
- Insulation gives a sleeping bag warmth. There are two types of insulation: synthetic and down (normally goose or duck down). Down is very light, very compressible, and normally more expensive. Synthetic insulation is bulkier, heavier, and less expensive than down. If down gets wet it loses its loft and it will NOT retain heat. If a synthetic bag gets wet it will normally retain about 80% of its insulating capability. Down is measured by Fill Rating or its ability to trap air for insulation. The higher the fill rating the better the down insulates and compresses. Some down bags, such as Kelty CosmicDown bags, use a treated down that is supposed to dry more quickly if it gets wet.
- The Hood encloses your head to prevent heat loss. Most mummy bags have a hood which can be closed tightly around your head.
- The Collar goes around your neck to help trap warm air inside of the sleeping bag.
- The Draft Tube helps prevent cold air from entering through the zipper.
- The Foot Box is the area at the bottom of the sleeping bag. Some bags have a tapered foot box which makes the bag slightly smaller and lighter and others use a larger foot box for added comfort.
- Some sleeping bags include small Pockets inside the bag and these can store small items such as mobile phone, wallet, etc.
Sleeping bag quality is a function of both materials and construction. At first glance some of the cheaper sleeping bags look very much like the more expensive and higher quality sleeping bags. Here are some factors related to the construction of a sleeping bag.
Zippers: Most mummy bags have a single zipper that goes most of the way to the foot box of the sleeping bag. Some bags have a shorter zipper on the other side of the bag. A few mummy bags, such as The North Face Aleutian, have a zipper that extends from the top of the bag to the bottom and all the way across the foot box. This type of bag could be completely unzipped and used as a blanket. Rectangular bags have a zipper that extends from the top of the bag to the bottom and all the way across the bottom of the bag.
Baffles are appendages designed to stop airflow. Higher quality and lower temperature bags may have a collar that goes around your neck to help prevent warm air from escaping. Many bags also have zipper baffles to block cold air that can enter through the zipper.
Offset Stitching: If you look at the higher quality sleeping bags you will see that the stitches on the outside of the bag do NOT penetrate to the same location on the inside of the bag. The inside and outside stitches will be offset from each other. Offset stitches helps prevent cold air from entering the inside of the bag through the stitching holes.
Vertical Baffles: Most sleeping bags have stitching that runs perpendicular to the length of the bag. Some higher quality bags use stitching that runs in the same direction as the length of the bag. These vertical baffles allow warmth to move from the warmer core of your body to the extremities of the bag.
Do NOT store your sleeping bag in the small stuff sack included with the bag. Store the sleeping bag uncompressed so that it does not lose loft. I store my sleeping bags under my bed and I only compress it before packing it for a trip. The fill material in the sleeping bag traps air and this trapped air insulates you from the cold. The fill material MUST retain its loft, or its ability to trap air, in order for it to be effective. As an alternative you can store the sleeping bag in a large, breathable pillow case or laundry bag. Make sure that the sleeping bag is NOT compressed. I do NOT recommend storing the sleeping bag in a mesh bag because spiders like living in the creases and spaces in the sleeping bag. Some sleeping bags also include a large storage bag as well as a small stuff sack.
You must be careful not to get your sleeping bag too close to flames. Some users, such as Coast Guard or Navy personnel, must use a certified flame retardant bag in their sleeping rack. Flame retardant bags may be harder to find and you may have to do some online research to find the fire rating.
A sleeping bag is a critical item when camping, backpacking, or for emergency preparedness. There are a number of accessories that can add warmth, versatility, and comfort to a basic sleeping bag.
- Sleeping Pads can add warmth and comfort
- Sleep Bag Liner can add warmth and comfort
- Sleep Bag Bivy can add warmth and protection