The 30 degree sleeping bag sizes are numerous. The bags designed for large people will have dimensions of 90 x 32 inches or so. Other bags will measure 77 x 33 inches. The 30 degree rating is fine for mild weather.
You should buy a bag that is of the right fit. Avoid those that are too large. Some extra wiggle room is nice, but too much room will make you feel cold. On the other hand, a too-tight bag is very uncomfortable. That is why it is important to read the measurements
Which Shape is Best?
Three types are available: the tapered, the cocoon or mummy style and rectangular. The rectangular is the roomiest. There are basically two rectangular sizes: the single and double. The double is big enough for two average size people. The rectangular style does not retain heat as well as the other bag shapes. But it is spacious and ideal for camping in the summer.
The cocoon style is more compact but is lighter. These are available in the same temperature rating as the other bags. However, it has superior heat retention compared to most rectangular bags. The tapered design is narrow at the bottom and wider around the shoulders. The 30 degree sleeping bag sizes are available in these three styles.
Which Style is Best?
The rectangular bags are probably the best known. They are widely available. For the casual campers, these will be sufficient. But if you camp in rugged places and love to explore, the cocoon and tapered styles are the better choice. They are designed to function under extreme conditions. These bags are also easily repacked.
Various materials are used to make these bags. The flannel-lined versions are soft and provide warmth. Those made of nylon are breathable. They dry rapidly and do not keep moisture. One of the best is poly-cotton. It is durable and can be used in different environments.
Filling Used in Sleeping Bags
Down fill offers the best in terms of lightness, insulation and durability. The only problem is they lose these properties when wet. Synthetic materials are heavier but heat retention is kept whether it is dry or wet.
Because there are many 30 degree sleeping bag sizes, you should have no problems finding the right fit. But you need to make sure that the bags are used only at the proper setting.