What does "loft" refer to in sleeping bags?

In the context of sleeping bags, "loft" specifically refers to the thickness of the sleeping bag and how much insulation it contains, which directly impacts its thermal efficiency. Loft is crucial because it measures the amount of air that is trapped within the insulation, which contributes to keeping the user warm. A higher loft typically indicates a better insulating capacity, as more air means better thermal retention.

This concept is particularly important when choosing a sleeping bag for different weather conditions, as a bag with a greater loft will provide more warmth in colder environments. Additionally, loft can also influence the overall performance and compactness of the sleeping bag when packed.

While size, weight, and material can each affect a sleeping bag's performance and usability, they do not specifically define "loft." Hence, understanding loft helps in selecting the appropriate sleeping bag for outdoor adventures based on the anticipated temperature and conditions.