Sleeping bags are generally compared by what characteristic?

Sleeping bags are primarily compared by their loft effect, which refers to the insulation's ability to trap air and provide warmth. The loft is crucial because the more the insulation can expand and fill the space inside the sleeping bag, the more air it can trap, leading to better thermal insulation properties. This characteristic directly affects the sleeping bag's warmth-to-weight ratio, comfort, and how it performs in various temperature conditions.

While weight, material, and color are important considerations when selecting a sleeping bag, they do not play as pivotal a role in determining the sleeping bag's thermal efficiency as the loft effect does. Weight is relevant for backpacking and ease of transport, and material is essential for considering durability and weather resistance, but loft is the primary indicator of how well a sleeping bag will keep you warm. Color might influence aesthetics and preferences but has no impact on the functional performance of the sleeping bag. Therefore, understanding loft is key for anyone looking to choose the appropriate sleeping bag for their needs.