Yes, you can carry milk in your cabin baggage, but the rules change depending on "who" the milk is for. If you are traveling with an infant or toddler (generally under age 2), you are allowed to bring "reasonable quantities" of breast milk, cow's milk, or formula in containers larger than 3.4 ounces. These are considered medically necessary liquids and are exempt from the standard 3-1-1 rule. You do not even need the child to be present to carry breast milk. However, if you are an adult just wanting a pint of milk for your cereal or coffee, you are strictly limited to the 3.4 ounce (100ml) limit, and it must fit in your quart-sized clear bag. If you need more milk than that for personal use, you must buy it after you pass through security. Always remember to remove large containers of "baby milk" from your bag at the checkpoint and inform the officer, as they will likely perform a separate scan of the liquid using a bottle scanner.