October 22, 2020
In life, there are few decisions that are more difficult to make than choosing a sleeping bag. It’s one of those items that can really make or break a backpacking or camping trip.
After all, your comfortability while sleeping outdoors depends on it. However, if you’re not an avid camper, you probably don’t see much of a difference when it comes to sleeping bag options (and there are a lot of them out there).
I’m here to tell you, though, that not all sleeping bags are created equal. Each one offers different temperature ratings, sleep systems, insulation, and a variety of additional features that can enhance your ability to get a good night’s rest.
To help you choose a sleeping bag that will be the best fit for you, I’ve put together a comprehensive guide below:
There are three key differences between backpacking bags and camping bags to keep in mind. Backpacking bags …
The differences between backpacking bags and camping bags are not always straightforward, though. When in doubt, go for a backpacking bag -- especially if you plan to do both activities. This way, you’ll get the most warmth without loading up the weight in your pack.
Sleeping bag temperature ratings indicate the lowest temperature they can keep an “average sleeper” adequately warm. It’s always best to pick a sleeping bag that has a temperature rating a little lower than the lowest temperatures you’re expecting. If you’re too warm, you can always open up the bag for more air, but there’s no way to make a cooler bag warmer.
It’s important to fully understand what temperature ratings and their terms mean. Here are some key definitions to help:
An “ISO” or “EN” rating allows you to make a reliable comparison between any two backpacking sleeping bags. “ISO” and “EN” ratings are standardized rating tests whose results are comparable (EN being the older version, ISO being the newer, slightly more consistent version).
ISO/EN testing gives a bag two separate temperature ratings: a comfort rating and a limit rating. “Comfort” rating tells you the lowest temperature a bag can keep a “cold sleeper” warm, and “limit” rating tells you the lowest temperature a bag can keep a “warm sleeper” warm.
If you’re not sure which one applies, women’s bags are often given “comfort” ratings, and men’s or unisex bags are often given “limit ratings”. Don’t see either of these terms listed? The temperature rating is probably a brand estimate and has not been ISO/EN tested.
Always keep in mind that a temperature rating can’t 100% guarantee that a given bag will keep you warm to your liking.
Ratings are most helpful for comparing different brands of bags, given that all brands test bags in the same way. Sleep system data is a better way to determine how warm you’ll be in varying conditions.
Real-life variables like humidity, wind, clothing, ground conditions, personal preferences, and your type of shelter always impact your warmth and comfort in a sleeping bag. The most important thing to keep in mind is your sleep system.
What’s a sleep system? It has three main components:
Sleeping bag test ratings are always based on a sleeper wearing long underwear and socks, and using a pad with an approximately 5.5 R-Value rating to make sure variables stay consistent across all brands and bags. So, if you use a less-insulated pad in the cold, or wear less clothing, your sleeping bag may not seem to perform to standard.
The first step to choosing the right sleeping bag for backpacking is your insulation type. Here’s a handy chart listing the main differences between synthetic and down fills.
No matter what type of insulation you choose, keep in mind that a lot of care is put into designing sleeping bags so that the distribution of insulation between the liner and the outer shell stays even.
Down bags often have baffled constructions of some kind, while synthetics have quilted, offset quilted and/or shingled constructions. These designs make sure that sleepers don’t end up with cold spots, regardless of the type of filling.
Down insulation is more expensive and more sought after than synthetic insulation because it’s lighter and packs down easily.
It’s also more durable, and can maintain consistent levels of warmth over a longer period of time. If properly cared for, down-insulated bags can even last decades! Here are answers to common questions about down insulation:
“Fill power” tells you the quality of down. The higher the number, the higher level of warmth for its weight. The most expensive down bags out there have the highest fill powers (closer to 800 rather than 500 fill-power) and are designed for extremely low temperatures or ultralight backpacking.
Down loses its insulation efficiency when it gets wet. For this reason, most sleeping bags treat their down insulation with a water-repellant.
Most down is sourced as a by-product of the meat industry. RDS (Responsible Down Standard) and TDS (global Traceable Down Standard) are designations that indicate that the ducks and geese providing down were treated humanely.
Synthetic insulation can provide quality performance at a lower price. Unlike down, its warmth efficiency is unaffected by exposure to water, making it an optimal choice for wet climates.
Most synthetics are made of polyester, listed as a variety of branded names. Sadly, there is no widely adopted “fill power” spec that can be used to cross-compare the performance of different synthetic fills.
Down/synthetic blend bags attempt to harness the best of both worlds. They are designed with synthetic on the bottom (so it compresses less), and down on the top (where it will loft better). The drawback to this model is that when rolled onto its side, the bag loses its advantage.
A sleeping bag’s insulation and its shape directly impact the weight most. High-efficiency insulations, such as synthetics or high-fill-power downs, provide more warmth for less weight. Since a bag needs more insulation to perform well in colder temperatures, it’s important to only compare bag weights of bags with similar temperature ratings.
Overall bag weight is the weight you feel carrying the bag in your pack. Insulation fill weight, however, only indicated the weight of the bag’s insulation. This is sometimes used to loosely determine bag warmth, since it intuitively seems that more fill makes a bag warmer -- but remember that a bag’s temperature rating is the most reliable indicator of warmth.
If a bag is sleeker and closer fit to the body, it will weigh less than bigger, roomy bags. Here are the three main bag shapes:
Mummy sleeping bags are designed with warmth and efficiency in mind. The fit is slim and close to the body, and it comes with a hood that can be tied tight around your head for extra warmth.
Keep in mind you’ll have to roll over with your bag instead of inside the bag when sleeping in a mummy bag.
Semi-rectangular bags are often referred to as a “modified mummy” or “barrel” shape. This designation is given to a variety of shapes that try to optimize warmth and roominess at the same time.
If you’re looking for the most roomy option, rectangular camping bags come in a simple large rectangle shape that offer the most space.
While sleeping, your body emits heat. Sleeping bags keep you warm by holding on to this heat that your body puts out. A closer-fit bag will be lighter than a bag of similar temperature rating that’s big and roomy.
The shapes listed above are, of course, generalizations. Dimensions can vary across different bags and brands. Sleeping bags also come in different sizes:
Kids’ sleeping bags are smaller, scaled-down versions of adult sleeping bags that come at a lower price point. Companies are unable to ISO or EN test kids’ bags, but brands still provide a temperature rating estimate.
Adult sleeping bags come in different sizes according to length. Most have a regular and a long size, though some also have a short size.
If you’re near the upper limit of a bag “fits up to” spec, test out that bag and the longer size to see which suits you best. The smaller bag will always keep you a bit warmer and will be a little more lightweight than the longer alternative.
Women’s sleeping bags are designed to fit the curves of an “Average woman’s” body. This means they are shorter in length, narrower at the shoulders, and have more room in the hips than a men’s or unisex bag.
Backpacking bags usually have an outer shell made of ripstop nylon or polyester. Shell fabrics are often treated with DWR (durable water repellent) to keep moisture from getting through to the fill. The inside lining typically has a brushed texture to feel soft and comfortable against the skin.
There’s nothing more annoying than snagging the zipper while opening and closing your bag -- not to mention it causes fabric wear and tear. Look for bags with a guard along the length of the zipper, or a cover on the zipper itself to avoid this issue.
To prevent warm air from escaping, some bags have draft tubes down the length of the bag behind the zipper. Some bags also have draft collars, or yokes that fit around your neck at the top of the bag to keep the warm air in.
Zipping Bags Together
For zipping bags together to work, one must have a left-hand zip and the other a right-hand zip of the same zipper type. Usually a men’s bag is a left zip and the women’s is a right zip. If combining bags proves difficult, you can also look into double bags made to fit two sleepers.
A pillow pocket is an opening where you can stuff clothing inside to create a make-shift pillow for your bag. If you’re using a bag without a pillow pocket, bringing a pillow from home or buying a camping pillow is always an option.
Some bags replace the underside insulation with a sleeve made to fit a sleeping pad. Pad loops can fit straps (sold separately) connecting your bag to the pad.
A stash pocket is a small pouch located near the chest at the top of the bag to keep essential items easily accessible.
Hoods (particularly if cinched tight around the head) can provide additional warmth to a bag. Some hoods even have “differentiated draw cords” with different thicknesses to help you distinguish which cord adjusts the neck and which cord adjusts the hood.
Leaving a sleeping bag packed down in a stuff sack for extended periods can prevent it from lofting and decrease its ability to insulate fully. This is why many bags come with a larger sack made of cotton or mesh for long-term storage.
A separate, soft sleeping bag liner can help extend the life of your bag, minimizing wear and keeping it fresh and clean. It can also add additional warmth, so that a single bag can be modified to work in a variety of climates.
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