The Domex Limit

Understanding Your Sleeping Bag’s Performance

A sleeping bag’s primary function is not to generate warmth but to retain the heat your body produces while you sleep. This heat retention is crucial for staying warm in cold conditions. Our temperature ratings reflect how well a sleeping bag can maintain warmth when external temperatures drop to a specified level.

Understanding Temperature Ratings

Sleeping bag warmth is influenced by individual factors such as metabolism, clothing, and sleep habits. Because of this variability, our temperature ratings serve as helpful guidelines rather than absolute measures. At Domex, we use the European EN ISO 23537-1:2002 standard for all our down sleeping bags to ensure reliable performance ratings.

This system provides three key temperature ratings:

  • Comfort – The temperature at which a standard woman can sleep comfortably in a relaxed position. Men typically find the sleeping bag comfortable at lower temperatures than this rating.

  • Lower Limit – The lowest temperature at which a standard man can sleep for eight hours in a curled position without waking. Warm sleepers can use this as an indicator of the bag’s suitability in colder conditions.

  • Extreme – A survival-only rating for a standard woman. Between the Lower Limit and the Extreme rating, discomfort and a strong sensation of cold should be expected, with a risk of hypothermia. This is not a recommended operating temperature but rather an emergency survival limit.

The Domex Limit

In addition to the EN ISO 23537-1:2002 ratings, we have developed the Domex Limit to offer further insight into real-world sleeping bag performance. Unlike the Extreme rating, which indicates survival conditions, the Domex Limit represents a practical, usable temperature range.

This limit is based on our extensive experience, as well as feedback from outdoor enthusiasts and testers. It assumes that the user is prepared with:

  • Thermal underwear (long-sleeve top and leggings)

  • Socks

  • A hat

  • A high-quality down or synthetic puffer jacket

  • A sleeping mat with an R4 or higher rating

By considering both the standardised EN ISO ratings and the Domex Limit, you can make a well-informed decision about which sleeping bag best suits your needs.