Unless you live on a farm or want to travel to the grocery store every day, you need a refrigerator to keep foods and drinks fit for later consumption. Keeping the fridge at the proper temperature is the key to minimizing food spoilage and loss. Several variables affect how you need to adjust your fridge settings.
One of the major reasons why people put food in the fridge is to slow the growth of harmful bacteria that could cause illness. Scientists have figured out that bacterial growth doesn’t really slow down significantly until temperatures reach around 40 degrees Fahrenheit.
No Freeze, Please
Even though bacterial growth slows at temperatures under 40 degrees Fahrenheit, many of the foods and beverages people like to store in the fridge have at least a small amount of water. If temperatures in the fridge dip below 32 degrees Fahrenheit, the water in the beverage or food can freeze. That can turn fresh fruits and veggies into an unappetizing, mushy mess once the food is thawed. It also can make it impossible to chug favorite beverages. Thus, the temperature in a fridge never should go below freezing.
Refrigerators are no different than other closed spaces in terms of physics. The warmest air in the fridge always will rise to the top, simply because it is less dense than cold air. This is a problem when trying to figure out the right temperature setting because the sensor for the fridge thermostat measures how warm or cold the fridge is in only one spot. To really get a good picture of where you should set the temperature dial, you should check the temperature at multiple spots within the fridge. This same phenomenon is what makes fridges with the freezer at the bottom more efficient than ones with the freezer at the top – the unit does not need to fight the natural tendency of cold air to sink and therefore cools better.
As you spot check the fridge temperature, a complicating factor is the amount of food and beverages in the appliance. If you have a lot in the fridge, the air cannot circulate properly and makes it much harder for the refrigerator to keep everything cool. Viewed from another perspective, the more you put in the fridge, the warmer the air in the fridge will get. You might need to set the temperature a little lower than normal to compensate for this if you’ve got more in the appliance than normal.
The General Rule
Given the fact you don’t want foods and drinks to freeze as you slow bacterial growth, the general rule of thumb is to keep your fridge somewhere between 32 and 40 degrees Fahrenheit, with 38 degrees being optimal. It’s best to keep your fridge only about medium full so the air can circulate to cool each item properly.