Understanding safe food temperatures can help you keep your food from growing harmful bacteria. You don’t want your ham sandwiches to send you – or, even worse, a friend or family member – to the bathroom or the hospital.
U.S. Food and Drug Administration (FDA)
says that bacteria grows at temperatures from 41 through 135 ° F (5 through 37.2 ° C). So, of course, you want your refrigerator at home to have a temperature below that. Usually, setting your fridge at around 36 ° F (2.2 ° C) and your freezer between -10 ° F and 10 ° F (-23.3 ° C and -12.2 ° C) makes your food safe.
Many refrigerators don’t have built-in thermometers. Rather, they have dials with numbers or arrows indicating "colder" or "warmer." Here’s the most accurate way to check the temperature: Purchase – at your grocery or hardware store - a thermometer to set inside the refrigerator. Place it on a middle shelf. Let it sit there overnight (or for at least four hours). Then look at the temperature. Is it above 36 °F? Turn the dial "colder." Below what you want? Adjust it "warmer."
If you can’t get a refrigerator thermometer, you can use your food thermometers and a cup of water. Place the cup of water in the refrigerator overnight. Then place your food thermometer in the cup and wait for the needle or readout to stop moving. Several checks may be necessary to be accurate. When you’re sure of the temperature, adjust the dial of your fridge.
Freezer temperatures should be between -10 ° and 10 ° F (-23.3 and -12.2 ° C). Freezers keep foods cold enough to preserve them for a few months, instead of a refrigerator’s few days.
Since you already have your refrigerator set correctly, place that same thermometer in the middle of the freezer and let it sit for a few hours. Then you can adjust your freezer dial as needed. (Of course, the cold water/food thermometer calibration won't work, since the water will just freeze!)