Freezers should be kept at a maximum temperature of zero degrees Fahrenheit in order to maintain food quality. Even lower temperatures, ranging from minus 10 to minus 20 degrees Fahrenheit, are recommended to maximize the lifetime of frozen food. Freezer temperatures above zero are not adequate for frozen food storage.
The freezer temperature is monitored on the unit's built-in thermostat, or with an appliance thermometer. Freezer owners can also determine the freezer's temperature by evaluating the consistency of foods kept in the freezer. For example, ice cream kept at the appropriate temperature is solid and hard. Freezers that are not able to maintain a temperature of zero degrees Fahrenheit risk increased food spoilage and food-borne illness.