You can bring toothpaste on a plane in your carry-on luggage only if the container is 3.4 ounces (100 milliliters) or smaller. This size limit is part of the TSA's 3-1-1 liquids rule, which allows passengers to carry liquids, gels, and aerosols in containers of 3.4 oz or less, all fitting within a single quart-sized, clear, resealable plastic bag

. If your toothpaste tube is larger than 3.4 oz, it must be packed in your checked luggage, where there are no size restrictions for toothpaste

. Exceptions exist for prescription toothpaste needed for medical reasons, which may be allowed in quantities greater than 3.4 oz if declared and used during the flight

. In summary:

• Carry-on: Toothpaste container must be 3.4 oz (100 ml) or less and fit in the quart-sized liquids bag.
• Checked luggage: No size limit on toothpaste.
• Prescription toothpaste: Larger amounts allowed if medically necessary and declared.

Following these rules helps avoid delays or confiscation at security checkpoints