The 3-1-1 Liquids Rule

Liquids, gels, aerosols, creams, and pastes in carry-on bags must each be in a container of 3.4 ounces (100 mL) or less, and all your containers must fit inside a single quart-sized, clear plastic bag — one bag per passenger.

There is no size restriction on liquids packed in checked baggage (beyond general hazmat rules for aerosols and flammable items).

Duty-free exception: liquids purchased after security in a sealed, tamper-evident bag with a visible receipt dated within 48 hours are allowed in carry-on even over 3.4 oz, as long as the bag stays sealed until you reach your final destination.

Medically necessary liquids (medication, baby formula/milk) are exempt from the 3.4 oz limit — see the medication and baby-item rules for details.