Yes, within strict limits: the TSA liquid limit lets you carry liquids, gels, aerosols, creams and pastes through security. Each container has to hold 3.4 oz or 100 ml or less. All of those containers together have to fit inside one quart size bag, one per traveler.
TSA calls this the 3-1-1 rule. It applies at every US airport checkpoint. That is why so many people repack their liquids the night before a flight.
The carry-on rule, stated precisely
Every liquid, gel, aerosol, cream or paste in your carry-on must sit in a small container. That container has to hold 3.4 oz or less, which is the TSA liquid limit stated on the official liquids rule page.
The size printed on the container is what counts, not how much liquid is left inside. A half full bottle that reads 12 oz still gets pulled, because the bottle itself is oversized.
All of those small containers need to fit in one quart size, zip top bag. Put that bag in a bin on its own at a standard checkpoint. PreCheck lanes often let it stay in your carry-on.
Medically necessary liquids and infant feeding
Liquid medication, saline and other medically necessary liquids are allowed over the TSA liquid limit. Tell the officer you have them before the bin goes through the machine, and keep them apart from your quart bag.
Breast milk, formula and juice for an infant or toddler traveling with you follow this same medically necessary allowance, in reasonable quantities for the trip.
Expect extra screening for anything over 3.4 oz that skips the quart bag. That is the trade for carrying more than the standard limit allows.
The checked bag rule, and where it differs
Checked baggage has no 3.4 oz limit for ordinary toiletries. A full size bottle of shampoo or lotion can travel in a suitcase headed for the hold.
Some liquids are still restricted or banned in checked bags outright, including most flammable liquids and gels. The question changes from how big the bottle is to whether it can fly at all.
The site has a full guide to liquids in checked baggage. It covers what changes once a liquid leaves the cabin.
Where carry-on and checked answers genuinely differ
| Situation | Carry-on | Checked bag |
|---|---|---|
| Shampoo, lotion, sunscreen lotion | 3.4 oz container max, in the quart bag | Any size allowed |
| Medically necessary liquids over 3.4 oz | Allowed, declared apart from the quart bag | Allowed, no declaration needed |
| Duty free liquids over 3.4 oz | Allowed only in a sealed STEB with receipt | Allowed, no bag required |
What actually happens at the checkpoint
Officers judge a liquid by the size printed on the container. They do not judge it by how full that container is.
The item that gets surrendered most is rarely a fragrance or a fancy skincare bottle. It is usually a plain, full size toiletry someone forgot to swap for a travel size before packing.
A quart bag stuffed past its zipper tends to get flagged and repacked on the spot. So does a second baggie taped to the first. Either one slows down the whole lane behind you.
Solids get waved through without a second look. That gap is exactly why a solid shampoo bar or a toothpaste tablet solves the problem before it starts.
International and duty free differences
Most countries outside the US run a version of the same rule. It is roughly 100 ml per container in one sealed bag, though the exact size and count can vary by airport.
Duty free liquids bought after your checkpoint are allowed over 3.4 oz, even on a connecting flight through a foreign airport. They must stay in a tamper evident bag with the receipt visible, per the same TSA liquids rule.
Break that seal, or open the bag before your final US checkpoint, and the liquid can still be taken. Buying duty free on the first leg of a connecting trip is the scenario that catches people out most.
Packing that avoids the problem entirely
A clear, reusable quart bag holds up better than a sandwich baggie. A sandwich baggie tends to tear at the seam under a full load. The WANDF clear TSA 3-1-1 quart toiletry bag is cut to the exact size TSA expects.
Decanting shampoo or conditioner solves the bottle size problem at the source. The humangear GoToob+ 3 pack sits right at the 3.4 oz limit. Reviewers say the seals hold up at altitude.
The simplest fix skips the TSA liquid limit altogether. A Ethique solid shampoo bar is a solid, not a liquid. It never touches the quart bag or its one bag per traveler cap.
Anyone packing a full quart bag can run the list through the site’s liquids packer tool first. It flags anything over the limit before you reach the checkpoint.
A screening officer has the final say on any item at the checkpoint, quart bag or not.
The bottom line
The TSA liquid limit is simple once you know it. It is 3.4 oz per container and one quart bag per traveler, with no credit for a bottle that is mostly empty. Medically necessary liquids and sealed duty free purchases are the two real exceptions, and each comes with its own paperwork.
Pack solids where you can and decant what you cannot. Related items like sunscreen, hairspray and aerosols all follow this same TSA liquid limit. Each has a few twists of its own.
Some links on this page are Amazon affiliate links. If you buy through one, Carry On Sizes may earn a commission at no extra cost to you. It never changes what we recommend. How this works.
More items in Liquids and Gels
Browse every item in the Liquids and Gels index.