Final answer:
You can carry liquids in containers of no more than 3.4 ounces or 100 milliliters on a plane in your carry-on luggage. Containers larger than this, such as juice boxes (250 milliliters) or soda bottles (1 liter), must be repackaged into smaller containers if they're to be brought on board.
Step-by-step explanation:
The size liquid you can carry on a plane in your carry-on luggage is limited due to security measures. The rule enforced by security agencies like the Transportation Security Administration (TSA) is commonly known as the 3-1-1 liquids rule. This rule allows passengers to bring liquids in containers that hold no more than 3.4 ounces or 100 milliliters.
To visualize this, consider that an eyedropper holds about 1 milliliter, which is much smaller than the allowed limit. A juice box often holds about 25 centiliters (250 milliliters), which would be too large for a carry-on. A typical soda bottle holds about 1 liter, equivalent to 1000 milliliters, and again, this greatly exceeds the limit set for liquids in carry-on luggage. Therefore, these examples must be repackaged into smaller containers if they are to be taken in carry-on luggage on a plane.