Question: how long should you cook 3 pounds of meatloaf?
Answer: Bake the meatloaf for 45 minutes. Bake for another 10 to 15 minutes. Spread the remaining 1/4 cup ketchup over the loaf. Bake until the middle of the loaf registers at least 155°F on an instant-read thermometer, 10 to 15 minutes more (about 1 hour total).