To determine the correct dosage of Tylenol or Advil/Motrin for a baby weighing 27 pounds, you can use the formula of 10 milligrams per kilogram of body weight. Since 27 pounds is equivalent to 12 kilograms, the initial dose would be 120 mg. You can increase it to 180 mg if needed, but do not exceed 5 doses in a day. If the Tylenol you have is 80 mg per milliliter, you would need to give 1.5 mL to reach 120 mg. Always follow the recommended dosages and consult with a healthcare provider if you have any concerns.