In 2026, the answer depends heavily on your specific airport's technology, as the world is currently in a "transition phase." The traditional 3-1-1 rule (3.4 oz/100ml containers in a 1-quart bag) still applies at most U.S. airports and many international hubs. However, several countries are officially scrapping this limit. Most notably, in the United Kingdom, major airports like London Heathrow, Gatwick, and Manchester have finished installing high-tech CT scanners that allow passengers to carry up to 2 liters of liquids in their carry-on. These scanners use 3D imaging to differentiate between water, alcohol, and explosive materials, eliminating the need to use small bottles or clear plastic bags. Similarly, several airports in Spain, the Netherlands, and Ireland have followed suit. However, if you are flying to a destination that hasn't upgraded its scanners yet, you may still be forced to discard large liquids upon arrival or at a connecting point. For 2026 travel, the safest bet is to check the specific "Security" page of your departure and connection airports; if in doubt, stick to the 100ml rule to avoid having expensive toiletries confiscated at a legacy checkpoint.