Each liquid, gel or aerosol in your carry-on must be in a container of 3.4 oz (100 ml) or less, all fitting in one quart-size (1 litre) clear bag, one bag per passenger. Medications and baby food are exempt but may be inspected.
The rule is named for 3.4 ounces, 1 quart bag, 1 bag per person. It applies in the US and, with the 100 ml / 1 litre wording, across the EU, UK and most of the world.
Counts as a liquid: drinks, creams, pastes, gels, aerosols, peanut butter, hummus, mascara, snow globes.
Exempt (with inspection): prescription medication, baby formula and food, breast milk, medically necessary liquids — declare them.
CT scanner lanes: some airports with new computed-tomography scanners let you leave liquids in the bag and, at a few, allow larger containers. The rule has not changed nationally; follow the lane signage.
Buy drinks after security or carry an empty bottle to fill at a fountain.
Related questions
Can you bring food through airport security?
Yes — solid food (sandwiches, fruit, snacks, chocolate) is fine in carry-on. Liquids and spreads (soup, yogurt, hummus, jam) fall under the 100 ml rule. Fresh produce and meat may be banned on arrival in another country. Full answer →
How long does airport security take?
Usually 10–30 minutes, but 45–60+ at large hubs during morning and holiday peaks. Many airports publish live wait times; PreCheck, Fast Track and off-peak departures are the reliable ways to shorten it. Full answer →
Airline, airport and government rules change without notice. Treat this as a starting point and confirm with the airline or authority for your specific trip. Request a correction if something is out of date.