Definition:
The 3-1-1 Rule refers to the Transportation Security Administration's rule for how much liquid travelers can take on an airplane in their carry-on bags. It does not prohibit you from putting larger sizes of liquids in your checked baggage.
3-1-1 refers to:
- Each liquid you want to carry on must be in 3.4 ounce (or less) container. That's the "3"
- The containers must be in 1 clear quart-sized plastic bag. That's a "1"
- Each passenger is allowed only 1 bag. That's the second "1"
The clear plastic bag limits the total amount of liquid you can take to what fits in the bag.