A sleeping bag rated to minus 5 degrees will not necessarily keep you comfortable at minus 5, because most labels show several different ratings for different sleepers.

Under the EN/ISO standard, the comfort rating is the temperature at which a typical cold sleeper stays comfortable, the limit rating suits a warm sleeper, and the extreme rating is survival only, not sleep.

Choose a bag whose comfort rating is 5 degrees colder than the coldest night you realistically expect, and remember your sleeping pad matters as much as the bag.

Women and cold sleepers should shop by the comfort rating, warm sleepers can use the limit rating, and everyone should test the bag at home before a cold trip.