The temperature rating for each sleeping bag is derived from a combination of factors. First, there’s a formula for the amount of down in a given size bag to reach a certain warmth rating. That’s just a place to start. Next, bags are tested in the lab according to EN 13537. This test procedure provides a lower limit and a comfort rating which are used to rate our men’s and women’s bags, respectively. Lastly, we rely upon user feedback from our employees, test team, and ambassadors.
There are many factors that determine how warm you will feel in a sleeping bag. Some of these factors include:
- What you wear. EN 13537 test ratings are based on the user wearing one layer of long underwear and a hat, but if you know you sleep cold, layer up!
- The sleeping pad you use. Your pad should have a minimum comfort range similar to your bag.
- What you eat before bed. Having a full belly of fuel will allow your internal furnace to keep you warm until morning.
- Where you pitch your tent. Sleeping on a tent platform, large rocks, or other thermally ineffective insulators can cause you to lose heat much quicker than sleeping on dirt or grass.