You can bring liquids on a plane in containers of 3.4 ounces (100 milliliters) or less per item, according to TSA rules and international regulations. All these containers must fit into a single clear, resealable quart-size (approximately 1 liter) plastic bag, and each passenger is allowed only one such bag in their carry-on luggage. This rule is commonly known as the "3-1-1" rule: 3.4 ounces per container, 1 quart-sized bag, 1 bag per passenger

. In practice, you can typically fit about 6 to 9 containers of 3.4 ounces each in the quart-sized bag, which totals roughly 20 to 30 ounces of liquids. However, the exact number depends on the container shapes and how you pack them

. There are exceptions to this rule for essential liquids such as:

• Baby food, formula, breast milk, and drinks needed during the flight
• Medically necessary liquids, gels, and creams, including prescription medications
• Ice packs or gel packs used to keep medical items cool

These exceptions can exceed the 3.4-ounce limit but may require additional screening

. Liquids in containers larger than 3.4 ounces must be packed in checked baggage. Also, any liquids purchased after the security checkpoint (such as duty-free items) can be brought on board regardless of size

. In summary:

• Maximum container size: 3.4 ounces (100 ml)
• All containers must fit in one clear, resealable quart-sized bag
• One bag per passenger
• Exceptions for baby food, medication, and medical necessities
• Larger containers must go in checked baggage

This rule applies broadly across the U.S., EU, and many international airports