A refrigerator thermometer helps ensure that a fridge remains at the correct temperature to keep chilled and frozen foods at an appropriate temperature. As of 2015, few refrigerators on the market have controls that show internal temperatures.
A properly functioning refrigerator should have an internal temperature at or below 40 degrees Fahrenheit. The freezer should be at or below 0 degrees Fahrenheit. Some steps to maintain proper fridge temperatures are to avoid overpacking the unit and to regularly check the internal temperature and adjust the setting if necessary. It is important to refrigerate foods as soon as possible to avoid bacteria growth.