Considerations in Selecting a Sleeping Bag for Backpacking

​Selecting a quality cold-weather sleeping bag is essential in preparing for the autumn and winter months, camping at elevation, and weathering sudden temperature shifts on the trail. Available options range from light, warm, down-filled bags that are susceptible to moisture to water-resistant, bulkier synthetic bags.

When purchasing a bag, consider its specific temperature rating, often defined under ISO (International Organization for Standardization) and EN (European Norm) rating systems. EN 13537 was the sole global standard until 2017 when ISO introduced a new standard (ISO 23537) that has emerged as an industry norm. Both systems use a similar approach of testing sleeping bags using heated manikins garbed in a hat, top and bottom long underwear, and a closed-cell foam sleeping pad.

There are four EN ratings, including EN Comfort, the temperature that enables an average female to comfortably sleep an entire night, and EN Lower Limit, the temperature at which the average male can enjoy eight hours of uninterrupted sleep. EN Extreme is the temperature at which an average woman can stay for six hours and not risk death from hypothermia. The ISO Comfort and Lower Limit ratings follow the first two EN ratings, with Comfort bags intended for those who tend to sleep cold and Limit for those who sleep warm.

US-based sleeping bag companies such as The North Face, REI, Mountain Hardwear, and Marmot all use EN and ISO ratings to various degrees. Some US companies that manufacture quality alpinist and backpacker bags, such as Western Mountaineering and Feathered Friends, do not use these standards and rely on their own internally developed systems. As a general rule, mid-range bags without either an EN or an ISO rating present a red flag to avoid that brand beyond mild weather excursions.

Another consideration with sleeping bags is their three basic form factors. Mummy bags are designed to reduce weight while maximizing warmth and offer a snug fit. Semi-rectangular, or “modified mummy” bags, are found in a number of shapes and deliver both warmth and room to stretch out. Rectangular bags provide room for one to both stretch out and turn over and may be unzipped and utilized as a comforter. Keep in mind that roomier bags tend to contain empty spaces and may sleep colder than the temperature for which they are rated.

When looking at sleeping bag insulation types, the major decision is between down or synthetic fill. The benefits of synthetic material include greater affordability and the ability to effectively insulate and protect, even when damp. The material also dries relatively quickly and is non-allergenic.

By contrast, down insulation is lightweight and stands up well to cold, provided that it stays dry. Compressing well, the material is highly durable and can retain warmth and loft for many years. Many of today’s quality down bags also undergo water-resistant treatments designed to protect them from damp conditions. One consideration among down-bag users is the treatment of geese and ducks that provide the filling material. Those concerned about procuring ethical down should look for bags that adhere to TDS (global Traceable Down Standard) or RDS (Responsible Down Standard) regimens.

Joshua Pratchard

Shop