• Use a thermometer to verify the temperatures in your refrigerator and freezer.Ryan McVay/Photodisc/Getty Images
  
  If you've ever found icy lettuce in your refrigerator, you know the dangers of setting its temperature too low. On the other hand, set it too high and you could risk bacteria growth and unsafe foods in your appliance. Following recommendations from the U.S. Department of Agriculture (UDSA) can help you get your refrigerator temperatures right.
  
  

Appropriate Settings

• The USDA says your refrigerator's temperature should be 38 to 40 degrees Fahrenheit. The frozen food compartment should be set at zero degrees Fahrenheit to maintain food quality for the longest possible time. Review your appliance owner's manual to determine how to set your refrigerator at these levels. After making an adjustment, allow 24 hours for the refrigerator to reach the new temperature setting.
  
  

Verifying Temperatures

• Even if you've set your refrigerator at the recommended temperatures, the USDA suggests you verify that the appliance has reached those settings. To check the temperature in the refrigerator, put a thermometer in a glass of water and leave it there for five to eight hours. Whirlpool suggests that you do this overnight so that the refrigerator door is not opened during the time the thermometer is inside. If the temperature is not in the recommended range after this period, adjust the refrigerator settings, and check the temperature again after providing the manufacturer's allotted time for the temperature change to take effect. When checking the freezer temperature, the USDA recommends putting a thermometer between frozen food packages for five to eight hours.
  
  

Saving Energy

• Using the recommended temperature settings can help you save energy when compared to setting your appliance at levels that are colder than necessary. You have other ways to save energy with a refrigerator as well. The American Council for an Energy-Efficient Economy recommends putting a dollar bill in the appliance doors when you close them and seeing if it stays firmly in place. If it doesn't, the door seals or gaskets may need to be replaced to prevent air leaks. The organization also suggests keeping your freezer full and defrosted to save energy.
  
  

Buying a New Refrigerator

• The government's Energy Star program says top-freezer models use up to 25 percent less energy than other refrigerator designs, and models with an ice or water dispenser in the door can use 20 percent more energy than those without one. Look at the yellow Energy Star labels on the showroom floor or online to compare the estimated annual energy use of refrigerators.