Find the right sleeping bag that meets you needs. There are many sleeping bags available. It can be difficult to decide on the right sleeping bag for you. Consider the sleeping bag weight. A heavy bag is not necessarily warmer. The warmth provided by the sleeping bag depends on the temperature rating, which is based on the type and thickness of insulation. The sleeping bag should fit your size. A sleeping bag that is too small is not a good choice, however a large sleeping bag will not be as as good as a right-fitting sleeping bag. A sleeping bag that is too large will be heavier than needed, and will have gaps under your feet which will have cold air. There are two basic shapes, rectangular and mummy shape. The mummy shape tapers in at the feet. This reduces the space to be insulated so improves heat retention at the foot of the sleeping bag.