Transparency is tough to find in the sleeping bag world!

Stone Glacier Sleeping Bags

When we set out to create a sleeping bag that was truly different than the rest, it quickly became evident that there was a lot of BS and marketing fluff in the sleeping bag world that could mislead even the most discerning user.


When we set out to create a sleeping bag that was truly different than the rest, it quickly became evident that there was a lot of BS and marketing fluff in the sleeping bag world that could mislead even the most discerning user. For example, a standard does not exist for temperature ratings! WTF...how is this possible? That means any company can call their bag any degree rating they want without any testing or repercussions. There is a scientific testing method that works great and is very accurate but it is not required, and many sleeping bag manufacturers don’t even publicize the results. What does this mean to you? Well, make sure you are comparing apples to apples when shopping for various bags. Just because a bag says, it is a zero degree bag and weighs 2lbs doesn’t necessarily mean that its warmth to weight ratio is better than another bag that says zero degrees and weighs 3lbs. Ask the brands you are looking at to provide the details of their temperature rating tests, and if they won’t, you should be very suspicious!

ISO Testing
Sleeping Bag ISO 23537 Testing at Kansas State University

The most common and widely used Temperature Rating testing method is ISO 23537. There are only a handful of institutions that perform this test and the most common for US-based companies is at Kansas State University. The results provided are based on various scenarios, and the output is categorized into three buckets:

T Comfort - Lower limit of the range in which the user is in a relaxed position, laying on their back and not feeling cold. Uses the metabolic rate of a female which is typically lower than a man’s.

T Limit - Lower limit of the range in which the user is in a curled up position and not feeling cold.Uses the metabolic rate of a male which is typically higher than a womans.

T Extreme - Lower limit of the range in which the user is in a curled up position and is at risk of health damage due to hypothermia. Uses the metabolic rate of a female which is typically lower than a man’s.

Through our research, we have found that most sleeping bag manufactures market and label the temp ratings of their sleeping bags based on the T Limit result. Many times this result is then rounded to the nearest 5° or 10° to categorize and name the bag. However, we also found that many brands do not publicize the results of their tests at all. This lack of consistency and transparency creates an inherent problem when comparing sleeping bags for overall weight. Although one sleeping bag may seem significantly lighter in overall weight, it may not have the same thermal regulating capabilities as others with the same marketed temperature rating.

Chilkoot 0° & 15° ISO Test Results

Stone Glacier Sleeping Bag ISO
Stone Glacier Sleeping Bag ISO

How we approach this... In the essence of transparency, we wanted to ensure the complete results of our sleeping bag temperature rating tests are available. As well, it was critical to us that the temp rating we marketed would truly be representative of the temperature at which our customers will be comfortable using our bags. So, it is our promise to you that we will always publicize and make the complete test results of our sleeping bags readily available. We want you to be confident in what you are using and have the data necessary to make an educated purchase.


Learn More about the Chilkoot Sleeping Bags

Chilkoot Sleeping Bag Design