The ideal way to pick a cozy enough bag is to go with one that handles a 10 degree colder climate than exactly what you're anticipating to be resting in. The last most significant consideration in selecting a bag is the insulation that is made use of in that bag.
The other sacrifice is the size or thickness of the bag. A mummy sleeping bag essentially will certainly be much smaller sized for bring around which is why it is a preference for many backpackers/hikers. The rectangular resting bag isn't as small yet because it's not common to be lugging it, apart from somewhere in a vehicle while getting to your intended location, the bulkiness of the bag is not as large a problem.
Prior to establishing your backpacking bag, be sure you shake it out a number of times. This will certainly help "fluff" it up and also increase the airspace. If your bag includes pockets, be cautious with simply what you determine to put in them. Prior to buying the bag, take note of the pockets different places.