If you are smoking at the ideal temperature of 225-250 F: Small Brisket (4-6 pounds): 6-8 hours Medium Brisket (7-10 pounds): 10-12 hours Large Brisket (11-14 pounds or more): 12-16 hours Rather than relying solely on time, it's best to use a meat thermometer to determine when the brisket is done! The internal temperature of the thickest part of the brisket should reach around 195-205°F (90-96°C) ;)