THE GOLDEN RULE: Never thaw a frozen turkey at room temperature.
By far the best method is to thaw the bird in the refrigerator (set no higher than 40F) and, be warned, this will probably take 3-4 days, depending on the size of bird you are dealing with.
To do this: Leave the bird in its original wrapping and place on a tray in the bottom of your refrigerator. Allow 5 hours per pound of bird – so for a bird of, say 14lbs, you would be looking at 70 hours (or just over 3 full days). Be sure to keep an eye on it during that time because you will periodically have to empty liquid out of the bottom of the tray … you don’t want to flood your fridge with raw turkey juice!
Quick method: Check that the turkey is in leak-proof packaging. If it is, put it, in its original wrapping, in a sink of cold water, breast side down. In the same way that ice cubes transfer their low temperature to a drink, so your frozen turkey will lower the temperature of the water. In other words, you’re going to have to change the water in the sink every half hour in order to maintain a consistent temperature. Allow half an hour per pound of turkey so, for example, the 14lb bird mentioned above is still going to take 7 hours to defrost. Cook as soon as you have completed this process.
I wouldn’t recommend using a microwave. The nature of microwave ovens means that the bones will become hotter quicker and the meat immediately around them may effectively start to cook, causing potential health hazards. If you feel you absolutely must use a microwave, follow the manufacturer’s instructions precisely and, again, aim to cook the bird immediately after.
Here are a couple of charts which may help when calculating thawing times:
Refrigerator thawing (weights represent a whole bird)
8 – 12 pounds ……… 1 to 2 days
12 – 16 pounds …….. 2 to 3 days
16 – 20 pounds …….. 3 to 4 days
20 – 24 pounds …….. 4 to 5 days
Cold water thawing times
8 – 12 pounds ……… 4 to 6 hours
12 – 16 pounds …….. 6 to 8 hours
16 – 20 pounds …….. 8 to 10 hours
20 – 24 pounds …….. 10 to 12 hours