If you have an upright freezer, you will need to keep the temperature regulated to -10° Fahrenheit (-22°C). To be sure it is set correctly, and calibrated, pick up a thermometer at a hardware or home improvement store.
Attach the thermometer with some wire or string beside the upright freezer's thermometer. Check to be sure both are at the same temperature after 24 hours. If your upright freezer is warmer than the thermometer, you may lower the temperature. If it is colder, then you will not have to do anything. Check the thermometers monthly to be sure your freezer is running cold enough to keep foods safe.