Turn the fridge thermostat dial to the midrange setting. For example, if the dial goes from 1 to 9, set the thermostat at 5.
Place a standard thermometer inside the fridge.
Wait 24 hours for the temperature to stabilize. Feel the inside temperature. If food and drinks are cold enough, the fridge is calibrated. Check the thermometer; if the temperature is around 41 degrees Fahrenheit, the fridge is calibrated.
Adjust the thermostat to a lower number to fix a fridge that is too cold. Adjust the thermostat to a higher number to fix a fridge that is too warm.
Wait 24 hours after adjusting the thermostat before checking or changing the temperature again. Keep adjusting the thermostat as needed until the appropriate temperature is achieved.