The 3.4-ounce liquid rule is the main limit TSA enforces at security checkpoints

TSA allows you to bring liquids, gels, and aerosols through security in containers of 3.4 ounces (100 millilitres) or smaller. Each container must fit this size limit individually — you cannot combine multiple smaller bottles to exceed 3.4 ounces in a single container. All your liquid containers go into one clear, quart-sized plastic bag, and that bag is what you remove and place in the security bin.

This rule applies to items you carry onto the plane in your carry-on bag. Checked baggage has no ounce limit for liquids, so you can pack full-size bottles, jars, and tubes in the suitcase that goes under the plane. The restriction exists because TSA screens carry-on bags less thoroughly than checked bags, and liquids in a pressurized cabin pose different safety considerations than those in the cargo hold.

The 3.4-ounce limit has been in place since 2006 and applies at every U.S. airport. International airports may have different rules depending on the country, so check with your destination airport before you travel.

Key Takeaways

  • Each liquid container in your carry-on must be 3.4 ounces (100 millilitres) or smaller, measured by the container's total capacity, not how full it is.
  • All your liquid containers fit into one clear, quart-sized plastic bag that you remove at security.
  • Full-size bottles and jars can go in your checked baggage with no ounce restrictions.
  • Common items that count as liquids include shampoo, conditioner, lotion, toothpaste, peanut butter, yogurt, and spray deodorant.
  • Solid items like bar soap, solid deodorant, and dry powder do not count toward the liquid limit.

What counts as a liquid under the 3.4-ounce rule

TSA defines liquids broadly to include anything that flows, spreads, or sprays. This covers obvious items like water, juice, and shampoo, but also includes creams, gels, pastes, and aerosols. Toothpaste, peanut butter, yogurt, jam, honey, and hummus all count as liquids because they have a consistency that spreads or flows.

Spray deodorant, hairspray, and sunscreen in pump or spray bottles are liquids. Solid deodorant and bar soap are not. Powders — including talc, baby powder, and protein powder — are not liquids, though TSA may open and inspect them. Medications in liquid or gel form follow the same 3.4-ounce rule, though you can bring reasonable quantities for your trip.

If you are unsure whether an item counts, the safest approach is to pack it in your checked bag. TSA's website has a searchable "What Can I Bring?" tool where you can type in specific items, but when in doubt, checked baggage avoids the problem entirely.

How to measure and pack your liquids correctly

The 3.4-ounce limit refers to the container's total capacity, not how much liquid is actually inside. A 3.4-ounce bottle that is half-full still counts as a 3.4-ounce container and is allowed. A 4-ounce bottle that is one-quarter full is not allowed because the container itself exceeds 3.4 ounces. Check the label or the bottom of the container for the total volume.

Ounces and millilitres are not exactly the same — 3.4 ounces equals 100 millilitres. If a container says 100 ml or less, it is within the limit. If it says 101 ml or more, it exceeds the limit. Many travel-size products are sold specifically at 3.4 ounces or 100 ml to fit this rule.

Place all your liquid containers into a single clear, quart-sized plastic bag before you reach security. A quart-sized bag is roughly 7 inches by 8 inches — most grocery stores sell boxes of these bags in the freezer section. Remove the bag from your carry-on and place it in the security bin along with your shoes and electronics. You do not need to remove individual containers from the bag; TSA will inspect it as a unit.

Items that are exempt or have special rules

Medications in liquid or gel form are exempt from the 3.4-ounce limit, but you must declare them to TSA. Place them outside your quart-sized liquid bag so the officer can see them. Bring a label or prescription bottle that identifies the medication. Infant formula and breast milk are also exempt and do not need to go in the liquid bag.

Duty-free liquids purchased after you pass through security at your departure airport can travel with you, even if they exceed 3.4 ounces. These items come in a sealed, tamper-evident bag with a receipt. You can bring them on the plane, but if you have a connecting flight, you cannot carry them through security at the connection — you would need to check them or leave them behind.

Frozen items like ice packs and frozen gel packs are allowed in carry-on bags as long as they are completely frozen solid when you reach security. Once they begin to thaw and become slushy or liquid, they fall under the liquid rule. Many travelers freeze gel packs the night before travel to may support they stay solid through the checkpoint.

What happens if you bring oversized liquid containers to security

If TSA finds a liquid container larger than 3.4 ounces in your carry-on bag, the officer will ask you to remove it. You have a few options: throw it away, check it in your baggage if you have time and your airline allows it, or leave it with a friend or family member who is not traveling. You cannot bring it through security, and you cannot board the plane with it in your carry-on.

This happens frequently with full-size bottles of shampoo, lotion, and sunscreen that travelers forget to pack in checked bags. It is not a violation or a fine — TSA straightforward will not allow it past the checkpoint. The best way to avoid this is to pack all liquids in your checked bag and bring only travel-size containers in your carry-on, or to use solid alternatives like bar soap and solid deodorant.

International travel and different airport rules

The 3.4-ounce rule applies at U.S. airports and on flights departing the United States. If you are flying internationally, the airport in your destination country may have different rules. European airports, for example, follow the same 3.4-ounce limit, but some other countries have stricter or more lenient policies. Check the website of your destination airport before you pack.

If you have a connecting flight through a U.S. airport, you will go through security again at the connection. Any liquids you bought after your first security checkpoint will be in a sealed duty-free bag, which you can carry through the connection. Liquids you packed in your carry-on from home must still follow the 3.4-ounce rule at every U.S. checkpoint.

Frequently Asked Questions

Can I bring a full-size bottle of shampoo if I check my bag?

Yes. The 3.4-ounce limit applies only to carry-on bags. You can pack full-size bottles of shampoo, lotion, sunscreen, and other liquids in your checked baggage with no ounce restrictions. Just make sure the containers are sealed and will not leak during handling.

Does toothpaste count as a liquid?

Yes, toothpaste is considered a gel and must follow the 3.4-ounce rule in carry-on bags. Travel-size toothpaste tubes are typically 0.85 ounces and fit easily in your liquid bag. You can pack full-size tubes in checked baggage.

What if my medication is a liquid and I need more than 3.4 ounces?

Liquid medications are exempt from the 3.4-ounce limit. Declare them to TSA at security and keep them outside your quart-sized liquid bag. Bring a label or prescription bottle that identifies the medication so the officer can verify it.

Can I bring a frozen water bottle through security?

Only if it is completely frozen solid when you reach the checkpoint. Once it begins to thaw and becomes liquid or slushy, it falls under the liquid rule and must be 3.4 ounces or smaller. Many travelers freeze water bottles the night before travel, but they often thaw during the airport process.

Do I need to remove my liquid bag from my carry-on at security?

Yes. Remove your quart-sized liquid bag and place it in the security bin along with your shoes, belt, and electronics. The officer will scan or inspect it separately. You do not need to remove individual containers from the bag.