This isn’t an easy question to answer because a lot of variables change the answer, like the side of the bird and the temperature of it when it goes onto the smoker. Weather can also play a factor in smoking time - a cold or windy day can affect your smoker’s performance, and so can altitude. If you’re using a Pit Barrel Smoker, be sure to check their guide for adjusting the vent for altitude. For reference, my 16-pound spatchcocked turkey took about 5 hours to smoke at 225-250F. Use a thermometer with a probe and ambient temp monitor to ensure success when smoking a turkey.