A rough estimate for cook time with a brisket is 1.5 hours per pound. That’s just to get you in the ballpark. It will still probably take another hour after that to finish it. Plus you need to wrap it in foil and let it rest for at least 1 hour, but 2 is better.
Example: 10 pound brisket X 1.5 hours equals 15 hour smoke at 225. Add in the extra hour to rest you are looking at 16 hours.
Example: 10 pound brisket X 1.5 hours equals 15 hour smoke at 225. Add in the extra hour to rest you are looking at 16 hours.