The recommended temperature for a freezer to keep food safe is at or below 0°F (-18°C) . However, the temperature may need to be adjusted by a few degrees to account for factors like location, humidity, or outside temperatures. It is important to keep perishable items cold, but not so cold that vegetables lose their freshness. It is also recommended to place an appliance thermometer in the freezer to make sure the temperature stays constant and to check it regularly. Keeping the freezer around 75-80% full helps retain cold air, but if it is fully filled, food may block the internal air vents, making it harder to distribute cold air throughout the freezer. If the power goes out, it is important to keep the freezer door closed as much as possible. When the door stays closed, a freezer can keep food at a safe temperature for around 48 hours.