Ideally, a whole, frozen turkey will have enough time to completely thaw before it goes into the oven or deep fryer. Although the USDA says it’s possible to roast a frozen or partially frozen bird, doing so will significantly increase the cooking time. This also runs the risk that the turkey will be unevenly cooked or worse, undercooked in places, which puts you and your guests at risk of getting sick.
The thawing guideline of one day in the fridge for every four to five pounds of frozen turkey is generally reliable, however, sometimes this isn’t enough. Folks pull their turkeys from the fridge after the allotted time only to find the birds are still somewhat frozen. Reasons for this include a refrigerator temperature that’s set lower than the standard of 37-40 degrees Fahrenheit or when the turkey is placed in the coldest part of the fridge. If this happens to you, don’t worry: you can always switch to the microwave or water-thawing method to finish the job in time for roasting.