The ideal temperature for a refrigerator is 40 degrees Fahrenheit or below, according to the U.S. Food and Drug Administration (FDA) . This temperature inhibits the growth of microorganisms that can cause foodborne illnesses, such as salmonella, listeria, and E. coli. The FDA also recommends that the freezer should be set at 0 degrees Fahrenheit. However, according to a post on Reddit, Canadian food safety rules demand a maximum of 39 F / 4 C. A general purpose domestic fridge should be at around 1-4 °C (just above the freezing point, and below 5 °C) . It is important to keep the refrigerator at the correct temperature to prevent fresh food from spoiling too quickly and to slow the growth of bacteria that can cause foodborne illnesses. It is also important to use a thermometer to ensure that the temperature is accurate, as some refrigerators may not be set to the correct temperature even if the temperature controls are set to a certain level.