You can bring liquids in containers of up to 3.4 ounces (100 milliliters) each in your carry-on bag on a plane. All these containers must fit into one clear, quart-sized (approximately 1-liter) resealable plastic bag. Each passenger is allowed only one such bag. This is known as the TSA 3-1-1 rule:

• 3.4 ounces per container,
• 1 quart-sized clear bag,
• 1 bag per passenger.

Overall, this typically amounts to about 25 ounces of liquid in total, depending on how many containers fit in the quart-sized bag. The rule applies to liquids, gels, creams, aerosols, and pastes like shampoo, toothpaste, lotion, and mouthwash. Exceptions exist for baby formula, breast milk, prescription medications, and duty-free liquids purchased after security, which can exceed the 3.4-ounce limit but must be declared. Frozen liquids that are completely frozen are not subject to this rule, but if partially melted or slushy, they are included. These restrictions apply to carry-on baggage; checked luggage can generally contain larger quantities of liquids but has other restrictions on certain dangerous substances. In summary, you can take up to about 25 ounces of liquids in total on a plane in carry-on bags, in containers no larger than 3.4 ounces each, all fitting in one quart-sized bag.