The world's most in-depth and scientific reviews of outdoor gear

How We Tested Backpacking Sleeping Bags

Monday May 13, 2019
The authors of the our backpacking sleeping bag reviews with a pile of several million goose feathers.
The authors of the our backpacking sleeping bag reviews with a pile of several million goose feathers.

Over the lifetime of our backpacking sleeping bag review, the team at OutdoorGearLab has tested more than 80 different bags hands-on. All the expertise gleaned from that considerable experience is directed into this, the latest addition. For this update bags were loaned out to certified mountain guides, Appalachian and Pacific Crest Trail veterans, Yosemite Search and Rescue personnel, and novice backpacking friends to gather a wide variety of perspectives and feedback. Their opinions were instrumental in the development of our performance criteria. The standards by which we evaluated these criteria are discussed below.

Although most sleeping bags now receive EN temperature ratings  two of the best manufacturers  Western Mountaineering and Feathered Friends  don't have their bags EN tested. Our warmth scores are thus a great way to get an unbiased opinion about their performance.
Although most sleeping bags now receive EN temperature ratings, two of the best manufacturers, Western Mountaineering and Feathered Friends, don't have their bags EN tested. Our warmth scores are thus a great way to get an unbiased opinion about their performance.

Warmth


If sleeping bag warmth were easy to measure, then we wouldn't need the rigorous protocol and copper mannequin of the European Norm (EN) temperature ratings. However, even casual use of a few bags with identical EN ratings reveals that there is a lot more to your perceived warmth than the number on the side of a sleeping bag.

To add the human element to our warmth ratings we first considered testing warmth while we were out actually backpacking, but the additional variables of the backcountry setting can complicate things. Basic stuff like fluctuating air temperatures and wind speed certainly have big effects. And subtler things, such as tent design, sleeping pad quality, underlying sleeping surface, and the number of tent buddies, also play an undeniable role.

To reduce these issues, we decided to test warmth in the "lab". Each night for three months we turned the thermostat down to 48°F and slept in a bag at home. Bags were selected randomly and switched each night so that by the end all had been used at least three nights. At the end, we reviewed our meticulous notes and identified noticeable differences in warmth between bags with similar EN ratings.

The difference between one of the lightest bags  the Therm-a-Rest Hyperion 32 (left)  and one of the heaviest  the Kelty Cosmic (right)  can be hard to identify be hand. Our digital scale  however  accurately measured it at 1.49 pounds.
The difference between one of the lightest bags, the Therm-a-Rest Hyperion 32 (left), and one of the heaviest, the Kelty Cosmic (right), can be hard to identify be hand. Our digital scale, however, accurately measured it at 1.49 pounds.

Weight


Measuring weight is pretty straightforward. To evaluate this performance criterion, we weighed each bag by itself on a digital scale. Any included stuff or compression sacks were weighed separately. The weight of these sacks is noted in our comparison table, but the 'Weight' score is based solely on the weight of the bag alone. We did this because we assume many users will buy a third-party compression sack to get their sleeping bag to pack down as small as possible.

The author exaggerates his discomfort with the Western Mountaineering MegaLite. The hood is very comfortable  but our 3 comfort testers don't think it's quite as comfortable as the Feathered Friends hoods.
The author exaggerates his discomfort with the Western Mountaineering MegaLite. The hood is very comfortable, but our 3 comfort testers don't think it's quite as comfortable as the Feathered Friends hoods.

Comfort


Comfort may be the most subjective aspect of sleeping bag performance. Interior dimensions can be accurately measured, but the softness of the fabric or the fit of a hood are harder to quantify, and no less important. To try to make it fair, we specifically recruited a diverse group of testers that sleep on the back, sides, or stomachs. The reported 'Comfort' score is an average of independent scores by at least three testers. It may not be perfect, but we're hopeful that it gives you some useful information.

We stuffed all the sleeping bags we tested  including this Western Mountaineering UltraLite  into this Granite Gear 11-liter compression sack and then measured the dimensions to calculate compressed volume.
We stuffed all the sleeping bags we tested, including this Western Mountaineering UltraLite, into this Granite Gear 11-liter compression sack and then measured the dimensions to calculate compressed volume.

Packed Size


All the sleeping bags we tested come with some sort of stuff or compression sack to store them in when backpacking. The effectiveness of these sacks, however, at compressing their respective sleeping bags varied greatly. Therefore, to measure packed size we compressed each bag into the same Granite Gear 11-liter compression sack. Minimum compressed volume was then recorded and used to determine the 'Packed Size' score. In the comparison table, we have also tried to indicate whether a bag comes with an effective "compression" sack or ineffective "stuff" sack.

All "full-length" zippers are not equal. The Feathered Friends zippers (red) are noticeably longer than the Western Mountaineering (blue) or Nemo (orange) zippers.
All "full-length" zippers are not equal. The Feathered Friends zippers (red) are noticeably longer than the Western Mountaineering (blue) or Nemo (orange) zippers.

Versatility


This aspect of performance is intended to evaluate the overall usefulness of each sleeping bag. To score it we considered how well a bag did if it got wet, the range of temperatures it could be comfortably used in, and whether it had any alternative uses besides being a single person sleeping system. Important factors that influenced versatility included the type of insulation, waterproof shell fabrics, the length of the main zipper, accessory vents, and heat-trapping neck baffles. After theorizing about each bag's versatility, we tested or theories in the field before assigning scores.

There are two straps on the underside of the Hyperion for attaching it to a sleeping pad. We really like that they're also removable if you don't want to use them.
There are two straps on the underside of the Hyperion for attaching it to a sleeping pad. We really like that they're also removable if you don't want to use them.

Features and Design


Features and Design serve as a catch all of the remaining aspects of sleeping bag performance. Points were given for useful features, such as convenient stash pockets or effective anti-snag zippers. To evaluate design, we examined manufacturer advertising material to try to identify the overarching intended purpose of a bag. We then scored each bag based on how well its design achieved this overall purpose. A bag like the Sierra Designs Cloud, for example, lost points because it has a 20°F rating but no good way to seal it closed. The Nemo Riff, in contrast, is advertised for its supreme comfort. Its hourglass-shaped accomplishes this and it has additional features like venting "gills" and a stash pocket that earned it a higher score.