The temperature inside a fridge should be between 35 and 38 degrees Fahrenheit but is largely determined by the cooling settings of the owner. The FDA requires all refrigerators used in food service to be under 40 degrees in temperature.
The purpose of a refrigerator is to slow down the growth of bacteria. At room temperature, the numbers of bacteria that cause foodborne sickness can double every 20 minutes. Freezing stops bacteria growth almost entirely, but damages or ruins food items, such as lettuce, strawberries, milk and eggs. Anything higher than 40 degrees will result in food spoiling too quickly and can also lead to food poisoning problems.