What is the airport liquids rule?

How does the 3.4 oz (100 ml) container limit work?

The TSA rule covers liquids, aerosols, gels, creams and pastes in the cabin bag and at the checkpoint. It allows one quart-sized bag of these items, with each container limited to 3.4 oz (100 ml) or less [1]. TSA says putting the items in the small bag and separating them from the rest of the carry-on helps screening [1], and directs passengers to pack containers larger than 3.4 oz (100 ml) in checked baggage [1].

TSA states the limit per item: it allows “travel-sized containers that are 3.4 ounces (100 milliliters) or less per item” [1]. Because the rule is written by container, a larger bottle is not brought within it by carrying less liquid [1]. Any liquid, aerosol, gel, cream or paste that alarms during screening requires additional screening [1]. For bag sizes and airline cabin allowances, see the carry-on baggage rules and fees guide.

Which items are exempt from the airport liquids rule?

TSA lists medications and infant and child nourishments as exemptions to its liquids rule [1]. Any liquid, aerosol, gel, cream or paste that alarms during screening will require additional screening [1].

The UK guidance takes a different route: it says frozen items are not usually allowed in hand luggage, for example liquid, food or ice packs, but points to exceptions for medicines, medical equipment and dietary requirements, and for baby food and baby milk [2]. Check the airport guide before travel.

How do duty-free liquids work on connecting flights?

TSA has a specific inbound international duty-free allowance. A passenger may carry duty-free liquids above 3.4 oz (100 ml) in the cabin bag if the liquids were purchased internationally and the passenger is travelling to the United States with a connecting flight [1]. The liquids must be packed by the retailer in a transparent, secure, tamper-evident bag, with no signs of tampering when presented for screening [1]. The original receipt must be present and the purchase must have been made within 48 hours [1].

The items inside the secure bag must be screened and cleared; anything that alarms or cannot be screened will not be allowed in the cabin bag [1]. TSA recommends packing all liquids over 3.4 oz (100 ml) in checked baggage, even when they are in a secure tamper-evident bag, and says liquids over that limit that are not in such a bag must be checked [1]. For travellers with checked bags, see through-check baggage.

Where do airport liquids rules differ between countries and airports?

The two official regimes are national: TSA sets the US checkpoint rule [1], while the UK government’s hand-luggage guidance covers boarding a plane in the UK [2]. The UK government says there are restrictions on the amount of liquids you can take in hand luggage and advises checking the liquids rules before travel [2]. It also says the rules for taking liquids through security in hand luggage have changed at some UK airports and advises passengers to check with the airport before travelling [2]. Countries outside the UK might have different rules for liquids carried as a transit or transfer passenger, and passengers should check with the relevant airlines and airports [2].

Airport security staff can refuse anything they consider dangerous, even if it is normally allowed in hand luggage [2]. The UK guidance allows only one lighter on board, to be kept in a resealable plastic bag on the person throughout the flight; a lighter cannot go in hold luggage or in hand luggage after screening [2]. Food and powders can obstruct x-ray images and may need a manual check, so the guidance suggests putting them in hold luggage to reduce delays [2].

Frequently asked questions

How big can a liquid container be in a US carry-on?

Each container must be 3.4 oz (100 ml) or less, and the containers must fit in one quart-sized bag [1]. TSA directs containers larger than that to checked baggage [1].

Can I take medication or baby food through US security?

TSA lists medications and infant and child nourishments as exemptions to its liquids rule [1]. Items that alarm during screening will need additional screening [1].

Can I carry sealed duty-free liquids through a US connection?

TSA allows duty-free liquids above 3.4 oz (100 ml) in the cabin bag when they were bought internationally and the traveller is flying to the United States with a connecting flight, provided they are in a transparent, secure, tamper-evident bag with the original receipt and the purchase was made within 48 hours [1]. The items must still be screened and cleared [1].

Are UK airport liquids rules the same as in the US?

The UK government publishes separate hand-luggage guidance and says liquid rules have changed at some UK airports, so passengers should check with the airport before travel [2]. It also warns that countries outside the UK may have different rules for transit or transfer passengers [2].

Can I take frozen food or ice packs through UK security?

The UK guidance says frozen items are not usually allowed in hand luggage, for example liquid, food or ice packs, with exceptions for medicines, medical equipment and dietary requirements, and for baby food and baby milk [2].

Related pages

Start with the carry-on baggage rules and fees guide, browse airports, and use the glossary for related terms. For checked bags and connections, see through-check baggage.

Sources

Sources checked on 18 October 2026. It covers the TSA rule for US checkpoints and the UK government’s guidance for UK airports; other countries’ screening rules are not covered here.

1. TSA: Liquids, Aerosols, and Gels Rule, checked 18 October 2026
2. GOV.UK: Hand luggage restrictions at UK airports, checked 18 October 2026