Guide
The TSA liquids rule for carry-on bags
Liquids, aerosols, gels, creams and pastes can go through a US airport checkpoint in your carry-on, but only in containers of 3.4 ounces (100 millilitres) or less, packed together in a quart-sized bag. Anything bigger belongs in checked baggage — with a few important exceptions for medication, baby food and duty-free purchases.
On this page
The rule in one paragraph
TSA's own wording is that you may bring "a quart-sized bag of liquids, aerosols, gels, creams and pastes" in your carry-on and through the checkpoint, limited to travel-sized containers of 3.4 ounces or 100 millilitres or less per item. TSA asks you to take that bag out of your carry-on at screening, because it speeds the process up. Containers larger than 3.4 ounces should go in checked baggage. This is what TSA refers to as the 3-1-1 liquids rule.
What counts as a liquid
The rule covers more than drinks. TSA lists liquids, aerosols, gels, creams and pastes, so a useful working test is: if it can be poured, sprayed, pumped, squeezed or spread, treat it as covered. In practice that catches most toiletries:
- Shampoo, conditioner, shower gel and liquid soap
- Toothpaste, mouthwash and gel or spray deodorant
- Moisturiser, sunscreen, foundation, mascara and lip gloss
- Perfume, aftershave and hair spray
Solid versions of the same products — bar soap, solid shampoo, stick deodorant, powder make-up — are not liquids and do not need to go in the bag. Switching a few items to solids is the simplest way to free up room. For any specific item, TSA's What Can I Bring? search gives its own answer, and TSA notes that the final decision on whether an item is allowed rests with the officer at the checkpoint.
The same test applies to food: peanut butter, yogurt, jam and sauces count as liquids or gels, while sandwiches, snacks and solid cheese do not. Our guide to bringing food through TSA goes through the main food types, frozen food and alcohol.
The exemptions that matter
Medically necessary liquids
TSA allows larger amounts of medically necessary liquids, gels and aerosols "in reasonable quantities" for your trip. They do not need to fit in the quart-sized bag, but you must tell the officer about them at the start of screening and take them out of your carry-on for separate inspection. Ice packs and gel packs used to keep medication cool are allowed in a frozen, partially frozen or melted state, and associated supplies such as syringes, pumps and IV bags are screened too. Officers may test the liquid; TSA states that screening never involves placing anything into it. Details are on TSA's disabilities and medical conditions page. If you are also arranging airport assistance, see our guide to booking special assistance.
Formula, breast milk and baby food
Formula, breast milk, toddler drinks and baby or toddler food (including puree pouches) are allowed in quantities over 3.4 ounces and do not need to fit in the quart-sized bag. TSA treats them as medically necessary liquids. Your child does not need to be travelling with you for you to carry breast milk and its cooling accessories. Tell the officer at the start of screening and take the items out for separate screening. TSA suggests clear bottles where possible, because liquids in pouches or bags may need alternative screening. The full list is on TSA's travelling with children page. For the rest of a trip with a baby, see flying with a lap infant.
Duty-free liquids on an international connection
This is the one that catches people out. If you fly into the United States from abroad and connect onto another flight, you pass through TSA screening again after customs, and the 3.4-ounce limit applies to anything in your carry-on. TSA allows duty-free liquids over that size only if all of these are true:
- They were bought internationally and you are travelling to the US with a connecting flight.
- The retailer packed them in a transparent, secure, tamper-evident bag, and the bag shows no sign of tampering.
- The original receipt is with them and the purchase was made within 48 hours.
Even then, anything that alarms or cannot be screened will not be allowed in the carry-on. TSA's own recommendation is to put liquids over 3.4 ounces in checked baggage, sealed bag or not. If your trip involves this kind of connection, our guide to booking US flights from the UK or Canada covers how much connection time to allow after an international arrival.
Does TSA PreCheck change the rule?
It changes the screening process, not the size limit. TSA says PreCheck members can keep 3-1-1 compliant liquids in their bag at screening, and that where a PreCheck lane is not available, showing a PreCheck boarding pass in the standard lane may still allow this. The containers still need to be 3.4 ounces or less. See the TSA PreCheck FAQ. If you are deciding whether to enroll, our comparison of TSA PreCheck and Global Entry covers the cost, eligibility and which one suits how you travel.
Checked bags and the carry-on allowance
The liquids rule is a security-checkpoint rule, so it applies to what you carry through screening, not to your checked suitcase. That creates a trade-off on fares that charge for checked bags: a full-size bottle of sunscreen can cost you a bag fee. Our baggage fees comparison shows what the main US airlines charge, and if you are on a restricted fare, check what Basic Economy allows in the cabin before you plan to travel with hand baggage only.
Some items have separate restrictions in checked baggage too, for example some aerosols. Check the individual item in TSA's search rather than assuming the hold is a free-for-all.
The reverse also applies: some things that must stay out of the hold have to travel in the cabin. Spare lithium batteries, including power banks and phone charging cases, are allowed in carry-on bags only and never in checked luggage. The watt-hour limits are in our guide to taking a power bank on a plane.
Flying back from another country
Other countries set their own screening rules, and they do not always match the US rule. On the outbound leg the TSA rule applies; on the way home, the security authority at your departure airport decides. Check that airport's guidance before you pack for the return journey. You still need acceptable identification at every US checkpoint as well.
A packing routine that avoids the bin
- Put every liquid, gel, cream, paste and aerosol you plan to carry on the table.
- Move anything over 3.4 ounces to checked baggage, swap it for a solid, or decant it.
- Pack the rest into one clear quart-sized bag that closes without straining.
- Keep medication, formula and breast milk separate, ready to declare.
- Put the bag at the top of your carry-on so it comes out in a few seconds.
Common questions
How big can liquid containers be in a carry-on?
Each container must be 3.4 ounces (100 millilitres) or less, and the containers go together in a quart-sized bag. Larger containers belong in checked baggage unless an exemption such as medication or baby food applies.
Is toothpaste a liquid for TSA purposes?
Yes. TSA's rule covers pastes and gels as well as liquids, so toothpaste goes in the quart-sized bag and the tube must be 3.4 ounces or less.
Can I bring medication over 3.4 ounces?
Yes, in reasonable quantities for your trip, if it is medically necessary. Declare it to the officer at the start of screening and take it out of your bag for separate inspection. It does not need to fit in the quart-sized bag.
Does TSA PreCheck let me bring bigger bottles?
No. PreCheck can let you keep 3-1-1 compliant liquids in your bag during screening, but the 3.4-ounce container limit still applies.
Can I carry duty-free alcohol on a connecting flight in the US?
Only if it was bought internationally within 48 hours, sealed by the retailer in a transparent tamper-evident bag, and you have the receipt. Anything that alarms or cannot be screened will be refused, so TSA recommends checking it in.
Sources
- TSA: Liquids, Aerosols, and Gels Rule
- TSA: Disabilities and Medical Conditions
- TSA: Traveling with Children
- TSA: PreCheck FAQ
- TSA: What Can I Bring?
- TSA: Power banks
Trailisse is an independent travel agency, not a government agency. This page is general information; the Transportation Security Administration's own guidance is the authority.