The optimal freezer temperature for maintaining the safety of frozen food is 0 degrees Fahrenheit or below. Frozen foods maintain their quality longer at a freezer temperature of -10 to -20 degrees Fahrenheit.
Although frozen food is safe to eat indefinitely if kept at 0 degrees Fahrenheit, the quality decreases with time, losing color, flavor and texture. The temperature of a freezer should be checked regularly, at least once a week. A refrigerator/freezer thermometer can be placed in the freezer to monitor temperature. Alternatively, checking to see that a container of ice cream kept in the freezer remains frozen brick-hard can help to ascertain an appropriate temperature.