The 3.4-ounce limit for carry-on liquids

You can bring liquids, gels, and aerosols through TSA security in your carry-on bag only if each container holds 3.4 ounces (100 milliliters) or less. This is the hard limit — a 3.5-ounce bottle will be confiscated, even if it is mostly empty. The rule applies to the container size, not how much liquid is actually inside.

All your liquid containers must fit into a single quart-sized clear plastic bag. You place this bag in a bin during screening, and TSA officers inspect it separately. You can bring one bag per person. If you have more liquids than fit in one quart bag, the extras go in checked luggage instead.

The 3.4-ounce rule exists because the TSA considers larger quantities of liquid a potential security risk. It applies to every flight from every U.S. airport, regardless of destination or airline.

Key Takeaways

  • Each liquid container in your carry-on must be 3.4 ounces (100 milliliters) or smaller, measured by container size, not fill level.
  • All liquid containers must fit inside one clear quart-sized plastic bag, which you remove and place in a bin during security screening.
  • Liquids larger than 3.4 ounces can go in checked baggage with no size limit, as long as they follow hazmat rules for your airline.
  • Common items that count as liquids include shampoo, conditioner, lotion, toothpaste, peanut butter, yogurt, and spray deodorant.
  • TSA provides free quart-sized bags at security checkpoints if you do not have one, though arriving with your own saves time.

What counts as a liquid under TSA rules

The TSA defines liquids broadly to include anything that flows, spreads, or sprays. This covers obvious items like water, juice, and shampoo, but also thick substances like peanut butter, yogurt, honey, and jam. Toothpaste, sunscreen, and lotion all count. Spray deodorant, hairspray, and perfume count because they are aerosols.

Solid items do not count as liquids. A stick of deodorant, a bar of soap, or a solid perfume bar can be any size in your carry-on. Powders (including makeup powder and protein powder) are also exempt from the liquid rule, though TSA may open and test them during screening if they look suspicious.

Gels sit in a gray area. Gel deodorant, gel insoles, and hair gel all count as liquids and must follow the 3.4-ounce rule. If you are unsure whether something is a gel or a solid, assume it is a gel and pack it in your quart bag.

How to measure and pack your liquids correctly

Check the label on the container itself — that number is what matters, not how much liquid is inside. A 5-ounce bottle that is half empty still violates the rule. Buy travel-sized bottles (usually 1 to 3 ounces) from drugstores, or transfer liquids into small containers you label yourself.

Bring a clear quart-sized plastic bag. TSA provides them free at checkpoints, but having your own speeds up screening. Lay all your liquid containers flat in the bag so they are straightforward to see and count. Seal the bag completely before you reach the security line.

Arrange your carry-on so the quart bag is straightforward to reach — near the top or in an outside pocket. You will remove it and place it in a bin on the conveyor belt, separate from your bag. This step takes only a few seconds if the bag is accessible.

Liquids in checked baggage have different rules

Checked bags have no size limit for liquids, but they must follow hazmat (hazardous materials) rules set by the airline and the Department of Transportation. Most common toiletries and foods are not hazardous, so a full-sized bottle of shampoo, a jar of jam, or a liter of olive oil can go in checked luggage.

Some items are restricted even in checked bags. Aerosol cans (spray deodorant, hairspray, sunscreen spray) are limited to one 18-ounce container per person in checked baggage, and they must have a safety cap. Flammable liquids like nail polish, nail polish remover, and certain perfumes are banned from checked bags entirely.

If you are traveling with a large quantity of a liquid — a full bottle of prescription medication, a liter of wine, or a gallon of cooking oil — check your airline's website or call them before you pack. Rules vary slightly by carrier, and some items require special declaration.

Common mistakes that lead to confiscation

Bringing a container larger than 3.4 ounces is the most common mistake. TSA officers will confiscate it at the checkpoint, and you cannot retrieve it later. There is no exception for nearly-empty bottles or for items you bought at the airport before security.

Packing liquids outside the quart bag is another frequent error. Even if each container is under 3.4 ounces, if they are loose in your carry-on, TSA will ask you to remove them and place them in a bag. If you do not have a bag, they may confiscate the items or delay your screening.

Forgetting that thick substances count as liquids causes confusion. Peanut butter, cream cheese, and hummus look solid but flow under pressure, so they must follow the 3.4-ounce rule. Sunscreen is another surprise — even though it feels like a lotion, it is a liquid and must be 3.4 ounces or less in carry-on.

What happens if TSA finds a liquid that is too large

TSA officers will stop you at the checkpoint and inform you that the container exceeds the size limit. You have three options: leave the item at the checkpoint (it will be discarded), place it in checked baggage if you have time to do so, or go back to the ticket counter and check your carry-on bag instead.

If you choose to go back and check your bag, you will lose time and may miss your flight. Most travelers choose to leave the item behind. There is no refund, and you cannot retrieve it later — TSA does not hold confiscated items.

The best approach is to check your bag before you leave home. Count your liquid containers, verify each one is 3.4 ounces or smaller, and pack them in your quart bag. A few minutes of preparation prevents a stressful moment at security.

International flights and TSA liquid rules

The 3.4-ounce rule applies to all flights departing from U.S. airports, including international flights. It does not matter where you are going — the rule is the same whether you fly to Canada, Europe, or the Caribbean.

When you arrive at your destination, you can buy full-sized liquids and pack them in checked baggage for your return flight. If you are connecting through another country, note that some airports have their own liquid rules. Most major international airports follow the same 3.4-ounce limit, but a few have stricter rules. Check your connecting airport's website if you are unsure.

If you buy liquids at a duty-free shop after passing through U.S. security, you can bring them on the plane in the sealed bag they provide. Do not open the bag or remove items from it, or TSA will confiscate them at your next checkpoint.

Frequently Asked Questions

Can I bring a full water bottle through security if I fill it after the checkpoint?

Yes. You can bring an empty water bottle through security and fill it at a water fountain or refill station after you pass the checkpoint. Many airports have these stations near gates. This saves money and avoids the liquid rule entirely.

Does the 3.4-ounce rule explore to medicine and baby formula?

Medicine in liquid form (like cough syrup) and baby formula are exempt from the 3.4-ounce limit in carry-on bags. You do not need to pack them in your quart bag. Tell the TSA officer you have these items before screening begins, and they will inspect them separately. Bring a prescription label or documentation if possible.

What if my deodorant is a spray but the can says it is only 2 ounces?

Spray deodorant counts as an aerosol liquid, not by the weight of the product inside but by the container size. A 2-ounce spray deodorant can go in your carry-on quart bag. The rule is that the container itself must be 3.4 ounces or smaller.

Can I bring multiple quart bags if I have more than one bag's worth of liquids?

No. TSA allows one quart-sized bag per person. If you have more liquids than fit in one bag, the extras must go in checked baggage. You cannot bring two or three quart bags in your carry-on.

Do I need to remove my quart bag from my carry-on at every security checkpoint?

Yes. At every U.S. airport security checkpoint, you must remove your quart bag and place it in a bin on the conveyor belt, just like you remove shoes and a laptop. This applies whether you are departing or connecting through another U.S. airport.