If you see a +20 degree score that would certainly indicate that the bag should be cozy enough for temperatures that are 20 levels or warmer.. And if you see a - 20 level score then it has actually been figured out that the bag needs to be cozy sufficient for minus 20 degree climate.
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.
If the sleep bags that you are taking a look at have not embraced the EN requirement, do not flip out. You could go by their temperature level measurement. The only difference is that these dimensions are to be used as a guideline just and do not think about the male/female distinction. Obtain a rest bag with added loft and also a reduced temperature level number if you're like me as well as are usually chilly whenever you sleep. The reduced the number, the cooler the exterior ambient temperature level can be where the bag will keep you cozy.