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How to Choose a Sleeping Bag

Your sleeping bag is probably the most important piece of camping gear you will ever own. It’s the core of your sleep system, the most vital component to ensure that you enjoy your time in the great outdoors. The quality of your overall camping experience comes down to your sleeping bag. And that means what bag you choose matters a lot. A good sleeping bag will be easy to pack down and carry, it will keep you warm and cozy, without overheating, and it will have the fit and features you need. But the wrong bag will leave you uncomfortable, shivering and cold in your tent. There are a plethora of bags available, with a huge litany of features, materials, and ratings. So we’ve created this guide to help simplify your process when shopping for a sleeping bag and narrow down the field to a bag that’s perfect for you.

What Makes Sleeping Bags Different From Eachother? How Do You Choose?

The largest differentiator between sleeping bags is the temperature rating. This means the most important question to ask yourself before you buy a sleeping bag is “Where am I going to use this, and how cold will it be?” If you don’t answer those questions first, you’re doing yourself a huge disservice. Camping gear is expensive and specialized. There’s no “Best” sleeping bag. Instead, there’s the best sleeping bag for you, which may be very different from the most expensive, or warmest bags.

Once you’ve figured out what approximate temperature range you’re planning on camping in, decide if you’re planning on hiking with this bag in your backpack. With sleeping bags, you’re generally dealing with three factors: Warmth, packed size and weight, and affordability. It’s pretty much impossible to find a bag that combines all three. There are plenty of very warm, lightweight bags out there, but they aren’t cheap. And there are plenty of affordable, warm bags out there that are heavy and hard to carry in a pack. Thekey is to find the sleeping bag that is the best balance for you. 

If you’ll primarily be driving to a campsite and then sleeping in your sleeping bag, its size and weight doesn’t matter so much, you won’t ever have to put it in your pack and carry it for miles. So warmth and affordability will be your priority. But, if you’re planning on long, overnight backpacking trips, you’ll want to find a bag that combines a smaller size, and lighter weight with the warmth you need. Once you’ve figured out what you’ll actually be using the bag for, you can narrow down your search based on these options.

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Down vs. Synthetic Sleeping Bags

Sleeping bags keep you warm by trapping a layer of air around you that insulates you from the outside temperatures. They do this using two main materials, down, or synthetic insulation. Both have their pros and cons, however, the largest differentiators are packability, weight, price, and performance while wet.

Down insulation is usually more expensive than synthetic insulations because it’s got a greater warmth to weight ratio - down will keep you warmer while weighing less. That said, down has its weaknesses, down is much more prone to wetting out and losing its warmth than synthetic insulators. However, modern down usually comes with some sort of water repellent coating to ward against this.

When you’re buying any down product, it’s worth making sure it’s traceable in some way. Environmentally conscious companies will include some sort of certification of their down to make sure it was harvested responsibly. Not only does making sure your down products are certified help the planet, but it also helps you make sure you end up with a high quality down bag, with no substitutes.

If weight is a priority, choose down, and just make sure to keep it dry. But if you don’t mind gaining a few grams, a synthetic bag can save you a lot of money, and is easier to care for down the road.

Sleeping Bag Temperature Ratings

Almost all sleeping bags come with some sort of temperature rating system, but it’s important to know how to use this system to find a bag that will work well for you. Look for bags with a rating system that says either “EN” or “ISO.” These standardized rating systems are a way for sleeping bag manufacturers to compare warmth, both among their own models, and with other brands. So a 30° bag will be warmer than a 40° bag, no matter which brand each comes from.

Beyond the rating system, there are several calculations that should go into choosing the warmth of your bag. The rating system usually has two numbers: a “comfort” temperature, and a “limit” temperature. Knowing what those temperatures mean is key.

Sleeping Bag Comfort vs Low or Limit Temperature Rating

The sleeping bag “comfort” temperature is the outside low temperature in which an average person will stay comfortable. The “low” temperature is the outside low temperature at which an average person will be able to sleep, with some discomfort. Obviously, those numbers are rather arbitrary, so think about your own habits, do you sleep warm, or cold?

If the bag has only one temperature rating, check whether it’s a unisex, men’s, or women’s bag. Men’s bags with only one number are generally the “limit” number, as are unisex bags. Whereas, women’s bags generally reflect the “comfort” temperature.

How to Choose the Right Sleeping Bag Temperature?

Look for a bag whose “comfort” temperature rating roughly matches the average nighttime lows in the areas you want to camp. It’s ok to get a bag that’s a little warm, it’s easy to unzip and cool off. But it’s much harder to make a bag warmer.

If you’re looking to extend the use-range of your bag, it’s easy to get a liner that ups the temperature rating of the bag by about ten degrees. This allows you to use a lighter bag in the summer, and up the warmth in the spring and fall.

Shapes of Sleeping Bags

Once you’ve figured out the materials and temperature rating you want, it’s time to pick what shape bag you’re looking for. The three main shapes are Mummy, Rectangular, and Tandem.

Mummy Sleeping Bags

Mummy sleeping bags are the lightest, and pack down the smallest, because they use less material, and instead hug your body shape. Mummy bags are best for folks looking for the lightest sleeping bags. The downside is that they can be uncomfortable and restrictive, especially for side sleepers. There isn’t much room to move around, and if you do tend to move a lot in your sleep, you may end up tangled in the bag.

Rectangle Sleeping Bags

Rectangular bags don’t pack down as small as mummy sleeping bags, but feel more like sleeping in a traditional bed, with sheets above and below you. They don’t pack down as small, and weigh more, but they’re the most comfortable option for car campers, and many can be unzipped to create a comforter for warmer nights.

Tandem Sleeping Bags

Finally, tandem sleeping bags are designed for two people. Tandem bags are great for couples, but aren’t efficient to hike with, since one person has to carry one big bag, instead of two people carrying smaller bags. Some mummy bags can also zip together to form tandem bags as well. If your not sure you and your partner want a tandem bag, hold off and figure out how well you sleep together. Tandem bags can be really uncomfortable if one of you tends to sleep warmer or colder than the other.

Sleeping Bag Sizes

If you’re pretty average-sized, you don’t need to worry too much about sleeping bag sizing, but it matters a lot if you’re very tall, usually above 6’. If your bag is too short, you’re going to have a cold chest and shoulders. Many bag makers sell “long” sized bags for people over six feet. They weigh a little more than average bags but make a huge difference for taller campers. Any good sleeping bag will have an approximate size chart.

Sleeping Bag Features

Sleeping Pad Compatibility

It’s important to remember that your sleeping bag is part of a sleep system. It needs to work together with your sleeping pad to keep you warm. If you don’t move around too much while sleeping, some bags, like those from Big Agnes, come with an integrated sleeve for the sleeping pad, which helps protect it and keep you warmer. It also makes for a lighter sleeping bag.

DWR Coatings

If you think you might be cowboy camping or sleeping in a bivy without a tent, it’s a good idea to look for a bag with a water resistant DWR coating to help protect it from dew. A DWR coating will also just help your bag stay clean longer, so it’s often worth the extra price.

Elephant's Foot Sleeping Bags

Some bags are specifically made to work in tandem with a puffy jacket, they have heavier insulation around the legs, and lighter, or no insulation around the torso. These are called “elephant’s foot style bags.” They pack down smaller and still keep you warm. However, this style of bag is only necessary if you’re willing to trade comfort for weight. For most folks, a regular mummy or rectangular bag will be much better, so make sure to avoid these elephant’s foot bags, unless you’re sure that’s what your after.

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