How To Choose A Sleeping Bag For Backpacking
Updated: Oct 5, 2019
As a major part of your sleep system, what you choose for a sleeping bag will have a huge effect on the quality of your sleep. And when I refer to a sleeping bag, I'm also including quilts as they serve the same function of insulating you on top.
Sleeping bags are constructed by sandwiching insulation (down or synthetic) between a shell material that is lightweight nylon or polyester. Just like with layering your clothing the trapped dead air creates a thermal barrier between you and the cold of the outside world. The thicker the insulation the colder temperatures you will be able to handle.
You need a sleeping bag that is warm enough for the temperatures you are in, have a good fit for you so you are able to get into a comfortable position sleeping and be light and compact enough to be easy to carry. And of course, be a price you can afford.
Sleeping Bag Vs Quilt
When zipped up a sleeping bag fully wraps around you while a quilt may have an enclosed foot box but the rest just drapes over you like a blanket. Since the sleeping pad provides the insulation under you your sleeping bag or quilt just have to insulate the top and sides.
For backpacking, you will want to choose a mummy style sleeping bag as it is the most efficient as far as weight, packed size, and warmth. It has a tapered shape with a hood to minimize the space you have to heat up. The rectangular sleeping bags are fine for car camping but are too bulky and heavy for backpacking.
A mummy bag is very versatile because you can use it fully zipped up for maximum insulation or completely unzipped and pulled over you like a comforter.
If you are claustrophobic a mummy bag can take some getting used to. When fully zipped up it feels a bit restrictive and doesn't let you sprawl out if that is the way you usually sleep.
For all but the coldest conditions, a quilt can be a good option. Lighter and more compact than a sleeping bag with the same insulation. Due to the lack of a hood, you will need to wear a hat or Buff to bed on cooler evenings.
Because the quilt drapes over you it can be pulled as tight or as loose as needed to regulate your temperature. Quilts often have tabs or straps that let you attach it to your sleeping pad to further insulate on colder nights.
Quilts that come from small custom companies are offered in different sizes and levels of insulation so you can get exactly what you want. This will usually cost a little more than getting a quilt from one of the big companies like Thermarest but that is a small trade-off for getting something made specifically for you.
If you are in a hammock with an under-quilt the top quilt is a great option as you just hop in and pull it over you. The same goes for people who roll around a lot when sleeping. The quilt gives a lot of room to adopt various sleeping positions. Since it is like using a blanket you don't really have to learn a new way to sleep so you may adapt to it quicker than a sleeping bag.
Sleeping bags are rated to be comfortable down to a specified temperature. Think of sleeping bags as being rated for seasons. You can get a bag that is good for summer, 3 seasons or winter.
A summer bag is rated down to around 0 Celsius, a 3 season bag rated to -10 Celsius and a winter bag rated -15 Celsius or lower.
Since the sleeping bags are rated by the lowest temperature it can be used for what a bag that is rated at least 5 degrees Celsius colder than the temperatures you expect to encounter. I often use a 3 season bag in the summer just half done up.
For the most consistent temperature ratings look for sleeping bags that are EN tested. This will usually be bigger brands that sell their sleeping bags in Europe. This is an independent test that rates bags with comfort, limit, and extreme rating.
You can compare the ratings of bags tested to this standard and be pretty confident of the warmth. A Mountain Hardwear Ratio 15 has an EN Limit Rating of -11 Celsius and The Northface Blue Kazoo has a Limit Rating of -10 Celsius. While they fit differently their insulating is almost identical.
These roughly translate as comfort is the lowest level that women or cold sleepers will be comfortable. The limit is the lowest rating that men or warm sleepers will be comfortable. The extreme is rated for not dying of hypothermia if used for six hours.
These ratings are based on wearing warm socks and a full thermal base layer so if you like to sleep undressed you have to factor getting a bag at least 5 degrees Celsius warmer.
If you are looking at a sleeping bag that isn't EN rated then look at reviews for how accurate others have found the rating the brand has put on the bag.
When choosing the temperature range of your sleeping bag you need to think about how you handle the cold.
Do you run hot or cold?
Spending a night shivering sucks so it's good to err on the side of bringing a bag that will handle slightly cooler temperatures which is why most of the year I use my 3 season sleeping bag even if it is overkill in the summer.
Sleeping bags usually come in different lengths. You want a bag that is rated for your height or more to give a bit of extra space. I'm 5'8" and use a unisex regular length which is rated for someone up to 6 feet tall.
Unisex bags generally come in two lengths, Regular and Long. A regular length bag is 6 feet and a long bag is 6'6". This is the rating of how tall of a person it will fit. Unisex bags are usually cut a little wider in the shoulders.
Women's bags are also available in Regular and Long but the lengths are shorter. A woman's regular is 5'6" and long is 6 feet. Women's bags are also usually a bit narrower in the shoulders. Since women tend to run colder than men women's sleeping bags will have more insulation compared to the same model in a unisex size.
You can have two bags with the same temperature rating and length but be cut with a different shape. When viewed from above you can see that some sleeping bags are super contoured to minimize any extra space. These bags are very efficient as far as warmth goes but can feel restricting. Due to the minimal material used in a highly shaped bag, they often are lighter than their roomier cousins.
Some mummy bags are cut extra narrow in the foot box forcing you to keep your legs together. If you like to be able to sprawl a little more than going a size longer can give your legs the extra room. Different bags also vary the amount of taper to the foot box allowing for more room for your legs to spread out.
My main sleeping bag is a Mountain Hardwear Ratio 15 and I chose that model because it had more room across the shoulders. The roomier fit allows me to roll around and find a comfortable sleeping position compared to tighter sleeping bags. The trade-off of the extra room is that it is more space to heat up. This works well for me as I give off a lot of heat so that doesn't tend to be an issue in all but the coldest temperatures.
Before we get into the specific types of insulation let's talk about the loft. Loft is a measure of how thick the insulation is. Thicker is warmer because it means more dead air is trapped insulating you from the cold. When looking at sleeping bags it is only the uncompressed insulation that will keep you warm.
The part of the sleeping bag that is under you does little to keep the cold out as you are compressing that insulation thereby squeezing out the dead air and making it thin. This is why we also need a sleeping pad to insulate under us.
Down is the plumes from under the feathers of geese or ducks. Goose down is generally the highest quality because the plumes are so fine. These fluffy bits have the benefit of being very light for the amount of insulation they supply. Additionally down has the benefit of being very compressible but puffs up again when you take it out of your backpack.
In the long term, down is a good choice because even though it is more money upfront the insulation will retain its loft for many years. If the down starts to clump or lose loft due to dirt and skin oil build up all you have to do is wash it with special down detergent and it will work like new. In between washings, you can puff up your down sleeping bag by tossing it in the dryer on low with a couple of tennis balls. This will break up the clumps and restore your sleeping bag to its original loft.
The main drawbacks of down are the price and the fact that it loses loft when wet. Companies are combating the later by treating the down with a water-repellent coating before it is sewn into the sleeping bag or quilt.
Many companies are trying to source their down in an ethical way by choosing to use down that is a by-product of the food industry.
There are different qualities of down that are rated based on their fill rating. Higher quality down has more loft per ounce of weight. Since the thicker the insulation the warmer it will be, higher-quality down gives the same insulation at a lighter weight. Fill weight ratings are labeled with numbers such as 550, 650, 850 or 900. The higher the number the lighter the weight for that level of warmth. Generally, the higher the fill weight rating the higher the cost.
Some people are allergic to down so keep this in mind when shopping for a sleeping bag. A warm sleeping bag that leaves you with puffy eyes and sneezing might not be the best choice.
Synthetic sleeping bags have the benefit of being less expensive, retain more heat when wet and dry quicker. But they are heavier for the same warmth, don't compress as small, and over time will lose their loft.
The synthetic insulation is made in sheets that are layered between the shell material. The layers are often overlapped like shingles on a roof to eliminate cold spots. Since synthetic insulation doesn't puff up as much as down, more has to be used to get the same level of loft.
If you are new to backpacking and want to keep the cost down then starting with a synthetic sleeping bag gets you into the game. I started with a synthetic bag and used it for many years. If you are a vegan or allergic to down then a synthetic sleeping bag will be a good choice for you as well.
When not on a trip store your sleeping bag uncompressed to minimize loss of loft over time.
Since your sleeping bag doesn't get rough use having a shell material that is very thin and light doesn't compromise durability. Sleeping bag shell materials are a fine weave nylon fabric that has a silky finish. Most companies treat the shell material with durable water repellancy (DWR) coating to help any water bead and runoff. This is useful for the occasional spill or condensation or dew build up.
For backpacking, you want to aim for the lightest sleeping bag that fits your needs and budget. Down sleeping bags are considerably lighter than their synthetic counterparts so unless you are allergic or opposed to down I suggest saving up the extra and get a down bag. Plus down sleeping bags have a longer useful lifespan. The down will maintain its insulative qualities for much longer than synthetic insulation will.
A good guideline for weight is:
Summer Bag ( 0 Celsius) - 2 lbs or less
Three Season Bag (-10 Celsius) - 2.5 lbs or less
Winter Sleeping Bag (-15 Celsius or lower) - 3.5 lbs or less
If you really want to save weight then consider using a quilt for summer or three seasons use as a Hammockgear.com Premium Burrow quilt rated to -6 Celsius weighs just over a pound.
Snag Free Zippers
You'll appreciate a snag-free zipper when you are trying to get in and out of your sleeping bag. Since the shell fabric is so light it can get caught in the zipper very easily. Test out before you buy.
You want a draft collar or tube around the hood and covering the zipper to help keep warm air in your sleeping bag. A zipper without a draft tube will have one side of your body getting cold.
If you and your partner want to share body heat then consider getting left and right zipper versions of sleeping bags from the same company. This will allow you to zip the two bags together.
In more high tech sleeping bags, companies have researched where we get cold and put more insulation in those areas. Many bags often have extra insulation in the foot box to keep your feet warm.
Sleeping Bag Liner
You can add a liner to add warmth or just keep the inside of your sleeping bag clean. If you like to sleep naked this is a good thing to use as your sweat and skin oils will make the inside of the bag dirty and affect the insulative quality of the insulation.
Some people like to organize their gear in stuff sack. A compression sack for your sleeping bag can help with this. I personally just stuff my sleeping bag at the bottom of my waterproof pack liner, but like most things, there is more than one way to solve a problem.
Whether your spare clothing in a stuff sack or a nice inflatable pillow, most of us need some sort of pillow to sleep comfortably. When sleeping in a tent, I use my clothing bag wrapped in a shirt, but in my hammock, I don't need a pillow.
The Wrap Up
If you want to enjoy yourself and perform well you need a good night's sleep. A good sleeping bag or quilt will make sleeping outdoors a much more comfortable experience and in cold conditions, can keep you alive.
Test out a bunch of sleeping bags at the store to find the one that fits you best and buy the best you can afford.
If you already have a sleeping bag, what are you using and how do you like it? Leave a comment below. :)