How Much Liquid Can Air Passengers Carry, and What Happens at the Checkpoint? Carry-On and Checked-Baggage Limits for Liquids, Alcohol, Batteries and Cash, with TSA Screening Volumes, Firearm Discoveries, PreCheck and REAL ID, 2010–2026

The limits on what air passengers may carry are spread across security guidance, hazardous-materials regulations, currency-reporting rules and state law. We compile them for passengers departing US airports and compare the liquid limits of Canada, the United Kingdom and the European Union, then describe the checkpoint with Transportation Security Administration (TSA) data. Carry-on liquids are limited to containers of 3.4 fl oz (100 ml) in one quart-size bag, while checked baggage allows toiletries of up to 17 fl oz per container and 68 fl oz per person and up to 5 litres of drinks of 24–70% alcohol; spare lithium batteries of up to 100 Wh, about 27,000 mAh at 3.7 V, need no approval, and cash above USD 10,000 crossing the border must be reported. UK and EU airports with approved scanners accept containers of up to 2 litres. TSA screened a record 906.7 million people in 2025, 0.3% more than in 2024, with a peak of 3,134,613 on 30 November and Sunday averages 1.27 times those of Tuesdays; January–August 2026 ran 0.6% below 2025. Firearms found at checkpoints rose 5.95-fold from 1,123 in 2010 to 6,678 in 2024, and 94% of those found in 2024 were loaded; per million people screened, the rate peaked at 10.20 in 2021 and fell to 7.39 in 2024. Atlanta led all airports with 451 firearms in 2023. Acceptable-ID compliance rose from 81% to 93% after REAL ID enforcement in May 2025. All inputs are public.