Q: Which temperature value for a sleeping bag is right for me?

This depends heavily on your personal sensitivity to cold: If you get cold easily (or are among women): It's best to always orient yourself towards the comfort temperature (Comfort) . This way you're guaranteed to have a cozy warm night. If you're rather insensitive to cold (or are among men): You can orient yourself towards the limit temperature (Lower) . However, for restful sleep, it never hurts to plan a little buffer. Rule of thumb: Choose your sleeping bag a bit too warm rather than too cold. In an emergency, you can open the zipper – but against severe cold in the tent, often only a warmer model helps.

Question 1

What do the different temperature ratings (Comfort, Lower, Extreme) mean for a sleeping bag?

Accepted Answer

The temperature ratings are based on standardized laboratory tests (EN ISO 23537) and help you find the right sleeping bag for your adventures. There are basically four categories:

Comfort (Comfort Temperature): Based on a "standard woman" (25 years old, 60 kg, 1.60 m). At this temperature, you as a woman can still sleep comfortably in a relaxed position without freezing.
Lower (Limit Temperature / Limit): Based on a "standard man" (25 years old, 70 kg, 1.73 m) in a curled-up position. At this temperature, a man just barely doesn't start to freeze.
Extreme (Extreme Temperature): A pure survival range for a standardized woman. At this temperature, there is a risk of severe hypothermia. This value should never be used as a purchase recommendation!
High (Upper Limit): The temperature at which a standard man can spend the night without excessive sweating (usually with the zipper open).

Question 2

Which temperature value for a sleeping bag is right for me?

Accepted Answer

This depends heavily on your personal sensitivity to cold:

If you get cold easily (or are among women): It's best to always orient yourself towards the comfort temperature (Comfort). This way you're guaranteed to have a cozy warm night.
If you're rather insensitive to cold (or are among men): You can orient yourself towards the limit temperature (Lower). However, for restful sleep, it never hurts to plan a little buffer.
Rule of thumb: Choose your sleeping bag a bit too warm rather than too cold. In an emergency, you can open the zipper – but against severe cold in the tent, often only a warmer model helps.

Question 3

Why are there such large differences between the values?

Accepted Answer

Due to biological reasons, women typically have less muscle mass and a different metabolism, which is why they get cold faster than men. The standardized tests account for this by providing two different reference values (Comfort for women, Lower for men).

Question 4

Can I rely 100% on the thermometer values?

Accepted Answer

The values are standardized laboratory values. However, your personal sensation of warmth outdoors in nature is influenced by many factors:

The right sleeping mat: Be sure to use a good sleeping mat (with sufficient R-value). Without insulation from below, the body cools down extremely quickly – no matter how good your sleeping bag is.
Physical condition: Anyone who is hungry, exhausted, or dehydrated will feel cold much faster.
Weather & tent: Wind and moisture in the tent can significantly worsen the perceived temperature.