For the food in your refrigerator to stay fresh for as long as possible—no ice crystals on the lettuce or bacteria breeding in warm spots—the refrigerator temperature should hover right around 37° F. In the freezer, a temperature of 0° F will keep foods thoroughly frozen.
Knowing that, the reasonable step would be to set your refrigerator to those temperatures. But the temperature controls on many refrigerators only allow you to choose from a series of numbers—say, from 1 to 5, with 1 being the coldest and 5 the warmest. Even when refrigerators have digital controls that allow you to set a specific refrigerator temperature, the settings aren’t always accurate. But the temperature-measuring equipment Consumer Reports uses in its tests is extremely precise, down to a fraction of a degree, so we can tell you exactly where to set your refrigerator temperature to achieve optimal freshness.