A quality sleeping bag is a critical component for any overnight expedition gear list. With so many bags to choose from, sifting through the options to find the right one for you can be challenging. This article is meant to shed some light on the types of sleeping bags and which are best for certain conditions.
Sleeping bags can be split into two categories based on their filler material: down and synthetic. Down bags are made with goose down, while synthetic bags are filled with different types of man-made insulation material. Both have advantages and disadvantages that are important to understand when picking your bag.
Goose down is an incredible natural insulating material with a very high insulation-to-weight ratio. Down is extracted from live geese, so that can raise some ethical concerns about how the geese are treated. Some manufacturers use down that’s certified to be humanely sourced, and usually these products are more expensive. Down bags are typically slightly lighter weight and pack down smaller than similar synthetic options.
Synthetic fillers vary depending on brand, but most are polyester-based materials that mimic the insulation and loft of down. Primaloft, FireLine ECO, and EraLoft are all examples of synthetic sleeping bag filler used by Nemo, Big Agnes, and Thermarest respectively. Each is slightly different, but the aim is a lightweight material that’s compressible, warm, durable, and water resistant.
One significant drawback to down is that it doesn’t perform well if it gets wet. Most synthetic bags will continue to provide insulation when wet, and this is not the case for down. Wet down clumps together, loses its loft, and no longer provides insulation. So, if you’re camping somewhere with lots of rain, then synthetic may be a better option. If you’re camping in the winter, then down is a good choice because it’s very warm—and freezing temperatures bring dry snow instead of rain, so there’s less risk of getting wet.
Historically, sleeping bag ratings were highly subjective and varied from one brand to another. The EN 13537 and ISO standards used now provide a universal measurement so consumers can compare sleeping bags from different brands. Sleeping bags are independently tested and given a comfort and limit rating.
Comfort Rating:Someone who usually sleeps cold will be comfortable at this temperature. Brands use this figure to list temperature ratings for women’s bags.
Lower-limit Rating:A person who is warm when they sleep will still be comfortable at this temperature. Manufacturers use this rating when listing the temperature of men’s bags.
Your intended use for your sleeping bag will determine what temperature rating is right for you. If you usually get cold when you sleep and you’ll be camping in temperatures around freezing, then a bag with a 15 or 20 degree Fahrenheit comfort rating will ensure you stay warm. On the other hand, someone who sleeps hot may be more comfortable when the temperature outside is between the comfort and limit ratings of their bag.
There are many attributes you can use to compare your sleeping bag options. After deciding your ideal temperature range, the most useful filters are weight, packed size, and price. When you’re carrying your gear, weight and packed size matter; and both factor into the price with more technology going into the lighter and smaller models.
If price isn’t a factor for you, then get the lightest, most packable bag in your desired temperature rating. Even if you’re not going far, carrying less weight feels good—and having a smaller sleeping bag makes it easier to fit the rest of your gear into your pack.
For most consumers, some balance between affordability and performance is ideal. If you are planning on lots of backpacking for several nights at a time, then it makes sense to pay more for a light and packable sleeping bag. If you’re just getting started or buying gear for a single trip, then a slightly heavier and bulkier bag may do just fine and will save some money.
I recently purchased a new sleeping bag to replace my work horse three-season bag that I’ve used for 20 years. This shows that paying more for quality gear is worthwhile in the long term. I’ll still use this old bag for summer camping, but the insulation no longer keeps me warm enough in the spring or fall; and it’s much bulkier for backpacking than newer ones.
First, I decided I wanted a bag with a limit rating around 30 degrees Fahrenheit. I am usually a bit warm when I sleep, so a limit rating of 30 degrees F will keep me warm if temperatures are slightly below freezing. Any colder than that, and I would either bring my winter sleeping bag—which has a comfort rating of 0 degrees F—or I’d plan to add more layers before bed.
Next, I had to decide between down or synthetic. This was tough for me because my outgoing bag is synthetic and I like knowing it will keep me warm even if it gets wet. However, in countless nights over two decades, there were only a couple times when my bag got wet in a storm and needed to hang up to dry the next day. Also, I really like how comfortable my down winter bag feels. This is purely a personal preference, but down has a softer feel than synthetic filler.
So at this point, I wanted a 30 degree F sleeping bag, and I was leaning toward down but would ultimately make up my mind based on evaluating the weight, packed size, and price of the 30 degree bags available. For me, weight and packed size were important; I also cared about price but was willing to pay a bit more for performance. A best-value option that was lightweight, packable, and not too expensive was my target.
I narrowed the search down to two bags within my price range that each weighed about two pounds and packed down to about seven liters. One option was down and the other synthetic. The down bag weighs slightly less and is a bit smaller when packed. So what did I choose? For this case, the down bag was the right choice for me. Hopefully this guide will help you work through the options to choose the right sleeping bag for you.