TSA 3-1-1 liquids rule: 3.4 ounce limit explained
One quart-sized bag, containers of 3.4 ounces (100 ml) or less. What is exempt and what counts as a liquid.
The rule in one line
TSA allows a quart-sized bag of liquids, aerosols, gels, creams and pastes in your carry-on, each in a container of 3.4 ounces (100 milliliters) or less. Containers bigger than that go in checked baggage. This is known as the 3-1-1 rule.
TSA says keeping the small bag separate from the rest of your carry-on makes screening easier, and that any liquid, aerosol, gel, cream or paste that alarms during screening needs additional screening.
What is exempt
- Medications. TSA lists medications as an exemption from the 3.4 ounce limit.
- Infant and child nourishment. Formula, breast milk, toddler drinks and baby food may exceed 3.4 ounces and need not fit in the quart bag. See baby formula and breast milk rules.
- Duty free from abroad, if flying to the US on a connecting flight. Duty free liquids over 3.4 ounces are allowed if they were bought internationally, are sealed in a transparent tamper-evident bag by the retailer with no signs of tampering, and come with the original receipt showing the purchase was made within 48 hours. The items must still be screened and cleared.
Food and drink examples
- Bottled water, soda, juice, soup, yogurt and creamy foods such as peanut butter and hummus are allowed in carry-on only at 3.4 ounces (100 ml) or less. See food in carry-on.
- Mini bottles of alcohol must fit comfortably into the single quart-sized bag.
How the US limit compares with the UK and Europe
Many UK and European airports also use a 100 ml limit, but some have raised it to 2 litres. See liquids rules by country and which UK airports allow 2 litres. TSA's liquids page, read on 5 November 2026, still states the 3.4 ounce limit.
Source: TSA Liquids, Aerosols, and Gels Rule and TSA food list. Checked 5 November 2026. The final decision rests with the TSA officer at the checkpoint.
Frequently asked questions
What is the TSA 3-1-1 rule?
One quart-sized bag of liquids, aerosols, gels, creams and pastes in your carry-on, each container 3.4 ounces (100 ml) or less. Larger containers belong in checked baggage.
Is 3.4 ounces the same as 100 ml?
Yes. TSA states the limit as 3.4 ounces (100 milliliters) per item.
Can I bring a full water bottle through TSA?
TSA lists bottled water as allowed in carry-on only at 3.4 ounces (100 ml) or less.
Are medications and baby formula exempt?
Yes. TSA lists medications and infant and child nourishment as exemptions from the 3.4 ounce limit. Tell the officer at the start of screening and expect the items to be screened separately.
Can I carry duty free liquids through TSA?
Only in the specific case TSA describes: duty free liquids bought internationally, travelling to the US on a connecting flight, sealed in a transparent tamper-evident bag by the retailer, with the original receipt from the last 48 hours.
Is the liquids rule different in the UK?
Many UK and European airports also use 100 ml, but some allow up to 2 litres. See our liquids rules page for the airport you fly from.