What liquids can you bring on a plane?

The carry-on rule is 3-1-1: each liquid, gel, or aerosol in a container of 3.4 ounces (100 milliliters) or less, all containers fitting in one quart-size clear bag, one bag per passenger. The container size is what counts, so a half-empty 6-ounce tube still gets confiscated. Peanut butter, yogurt, and snow globes count as liquids; TSA's rulings on this are a genre of literature.

The exceptions are humane: medications, baby formula, breast milk, and juice for infants can exceed the limit; declare them at screening. Duty-free liquids in sealed tamper-evident bags are also allowed under specific conditions.

Checked luggage has no 3-1-1 limit, so full-size shampoo flies fine below deck. And when unsure about any object, TSA's What Can I Bring tool at tsa.gov gives an official answer in seconds, which beats debating a bottle of hot sauce at the checkpoint.