US outdoor manufacturers and retailers have adopted a new sleeping bag temperature rating standard called EN13537 that was originally developed in Europe. While it helps consumers compare different sleeping bags, it can be a bit difficult to understand.
There are three ratings that you need to pay attention to when evaluating a sleeping bag rated using EN13537: Comfort, Lower Limit, and Extreme.
- The comfort rating is for women (I don’t know why they didn’t just label it women.) Women need more insulation when they sleep than men.
- The lower limit is for men and designates the lowest temperature at which a man can remain comfortable in the sleeping bag, provided he’s wearing long johns and sleeping on a 1″ pad.
- The extreme limit designates the coldest temperature you could survive without freezing to death. I find this an odd thing to put on a consumer tag, but it is what it is. Beware of this rating. Online retailers sometimes quote it as the lower limit or the comfort rating of the bag (#2) because they don’t understand what information to print.
Accurate Product Listings
REI is one of the leading proponents of the EN13537 temperature rating standard in the states, and their sleeping bag product descriptions demonstrate their commitment to clearly articulating the recommended temperatures for women and men. For example, if you check out the Specs tab of any sleeping bag sold at REI, you’ll see the following lines listed.
- EN lower limit (rating for men) ## degrees Fahrenheit
- EN comfort (rating for women ## degrees Fahrenheit
The EN13537 sleeping bag temperature standards provides consumers with the ability to make relative comparisons of the insulating value of different sleeping bags. That’s a good thing and sleeping bag temperature ratings have become much more realistic.SectionHiker is reader-supported. We only make money if you purchase a product through our affiliate links. Help us continue to test and write unsponsored and independent gear reviews, beginner FAQs, and free hiking guides.