Today's sleeping bag technology is so advanced that certain bags can even be used in the Arctic. With this technology comes a rating system to inform you what temperature you can use the bag in. Knowing how to read these ratings can make the difference between a restful night's sleep or a restless night of tossing and turning. In extreme cases, even hypothermia can result from choosing the wrong sleeping bag.
Locate your sleeping bag's temperature rating tag. It is usually on the inside of the bag, sometimes hidden within a pocket.
Read the tag. Some bag ratings simply give a number in degrees. That number estimates the coldest temperature for which the bag provides insulation.
Look at the tag to see if any additional information is given. If the rating shows two bars -- one for male, one for female -- look at the specific bar for your gender and read the rating. There may be a blue bar and an orange bar. The blue bar shows the temperature range at which you are likely to be cold. The orange bar is the estimated warm range.