This sleeping bag buying guide is a general overview of types of sleeping bags, features of sleeping bags, sleeping bag care, and tips on how to be more comfortable in your sleeping bag. There are several key features to consider when purchasing a sleeping bag. The most critical features to consider are the style, the shell, the lining, the fill, and the temperature rating.
Sleeping bags basically come in two main styles, rectangular and mummy. Rectangular bags usually cost less and offer more room, but are heavier and don’t offer as much warmth. Mummy bags cost more, hug your body, are lighter and offer more warmth. Some rectangular bags taper as they go to the feet or are rounded at the base. Not a true mummy bag these offer a compromise between the two styles.
Mummy bags are wider at the shoulders and taper down the sides to your feet, hugging your body. The tapered design of a mummy bag gives it a performance advantage. Be removing the unused space around your body, you have a smaller volume for your body to warm. Mummy bags may also have hoods and draft collars, which will help prevent warm air from escaping from the bag. The tapered shape of a mummy bag uses less material and less fill, resulting in a lighter bag. Mummy bags may be too tight fitting for larger individuals, and others may not like the tight fit of a mummy bag.
A rectangular bag resembles a rectangle when rolled out. The edges are 90 degrees (square). Rectangular sleeping bags tend to be heavier thanr mummy bags, and due to the extra volume inside the bag they are not as thermally efficient. The rectangluar shape is not as effective and preventing warm air from escaping the sleeping bag. Rectangular sleeping bags typically are less expensive than mummy bags, and because they are considered roomy, are more comfortable for larger people.
Hybrid bags combine the shape of mummy bags with rectangular bags. They are also called tapers and semi-rectangular sleeping bags. They resemble a rectangular bag but taper down slightly as they go toward the feet and will typically have a rounded foot area. The removed space means lighter weight and less volume to keep warm at night. Hybrid sleeping bags offer a good balance of price, weight and warmth.
Overbags and Bivy Sacks
Overbags are used with a sleeping bag to extend the temperature range of the sleeping bag when additional warmth is needed. Overbags can also be used in warm conditions as a light sleeping bag. Overbags may also be used to supplement the waterproof abilities of a sleeping bag.
Bivy sacks are different. Typically waterproof and made of a breathable material, a bivy sack is used when sleeping under the stars, in extreme wet conditions, or winter camping. Both overbags and bivy sacks (you may hear these terms interchanged) increase the range of use of your bag, but cut down on how well the materials breathe.