Liquids in carry-on: the 3-1-1 rule

The rule is called 3-1-1, and the numbers are the whole point. It covers anything liquid, gel, cream, paste or aerosol in your carry-on.

3: each container holds 3.4 ounces (100 ml) or less. The size printed on the container is what counts, not how full it is. A half-empty large bottle is still a large bottle.

1: all of them fit in one clear, quart-size bag.

1: one bag per traveller.

The bag should close, and you take it out of your carry-on at the checkpoint if asked. The TSA rule page is the source for the details, and it is worth reading before a trip, as screening procedures can change.

Common exceptions

TSA allows larger amounts of some items, typically medication, baby formula, breast milk and food for infants, but you should tell the officer and keep them separate from the bag. The TSA page lists what applies. Do not rely on a blog, including this one, for the fine print.

Checked bags and other countries

A bigger bottle can go in checked luggage, usually without trouble. Pack it in a sealed bag in case it leaks.

Outside the United States, limits often match the 100 ml rule, but not always, and some airports have scanners that change the procedure. Check the airport and the airline, especially on a trip with a connection. ## What to do in practice

Decide what must be liquid, and swap the rest for solids. Bar shampoo and solid deodorant do not count against your bag. Read how this works in a longer trip in the 10-day carry-on list.