The 3.4-ounce rule for carry-on bags
You can bring liquids, gels, and aerosols in your carry-on bag only if each container holds 3.4 ounces (100 milliliters) or less. This is the standard rule enforced by the Transportation Security Administration (TSA) at U.S. airports. The limit applies to each individual container, not the total amount you bring.
All your liquid containers must fit inside a single quart-sized clear plastic bag. You place this bag on the security conveyor belt separately, just like you would your shoes or belt. If a container is larger than 3.4 ounces, even if it is only partially full, TSA officers will not allow it through the checkpoint.
The 3.4-ounce limit exists because liquids are harder to screen than solid items. Security staff cannot easily see inside opaque bottles, so the small-container rule reduces the volume of liquid that could potentially pose a risk on an aircraft.
Key Takeaways
- Each liquid container in your carry-on must be 3.4 ounces (100 milliliters) or smaller, and all containers together must fit in one quart-sized clear plastic bag.
- Common liquids that count toward this limit include shampoo, conditioner, lotion, toothpaste, peanut butter, yogurt, and liquid medications.
- You can pack full-sized bottles of liquids in your checked baggage with no size restriction, as long as they follow hazardous materials rules.
- Duty-free liquids purchased after security screening can be carried on if they are in a sealed, tamper-evident bag, but only one bag per passenger.
- Different countries have different liquid rules, so check the rules of your destination country and any connecting airports before you travel.
What counts as a liquid in the 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 includes less obvious ones: toothpaste, peanut butter, yogurt, jam, honey, and hummus all count as liquids under TSA screening rules.
Gels and aerosols follow the same 3.4-ounce limit. Gels include hair gel, aloe vera gel, and thick creams. Aerosols are anything in a pressurized spray can, including deodorant, hairspray, and sunscreen spray. A solid stick of deodorant or a bar of soap does not count as a liquid and can be any size.
Medications in liquid or gel form are allowed in carry-on bags in quantities larger than 3.4 ounces, but you must declare them to TSA officers at the checkpoint. Bring the medication in its original labeled container so officers can verify what it is.
Packing liquids in your carry-on bag
You need a clear, quart-sized plastic bag to hold all your liquid containers. A quart-sized bag is roughly 7 inches by 8 inches — most airports sell these bags if you do not have one, though bringing your own saves time and money. Place the bag on top of your other carry-on items so it is straightforward to remove at security.
Arrange your containers so the smallest ones are on top and larger ones on the bottom. This makes it easier for TSA officers to see each container clearly. If a container is leaking or appears damaged, place it in a separate small bag inside the quart bag to prevent spills on your other items.
Remove the quart bag from your carry-on before you reach the security conveyor belt. Place it in the bin with your shoes, belt, and jacket. Do not wait until the officer asks — this speeds up the screening process and shows you understand the rules.
Liquids in checked baggage have no size limit
You can pack full-sized bottles of shampoo, lotion, cologne, and other liquids in your checked bag with no ounce restriction. Checked baggage is screened differently than carry-on bags, so the TSA does not explore the 3.4-ounce rule to items you check.
However, hazardous materials rules still explore to checked bags. Flammable items like lighter fluid, paint thinner, and some nail polish removers are banned from checked luggage entirely. Aerosols like hairspray and deodorant are allowed in checked bags in limited quantities — usually one container per passenger. Check the TSA website or call your airline before packing anything you are unsure about.
Pack liquids in the center of your checked bag, surrounded by clothing or towels as a cushion. Even though baggage handlers are trained to handle luggage carefully, turbulence and rough handling can cause bottles to leak. A sealed plastic bag around each liquid container adds extra protection.
Duty-free liquids and the sealed bag exception
If you purchase liquids at a duty-free shop after passing through security, you can bring them on the plane in your carry-on bag, even if they exceed 3.4 ounces. The items must be in a sealed, tamper-evident bag provided by the duty-free retailer. You are limited to one bag per passenger.
This exception only works if you are traveling to your final destination on the same ticket. If you have a connecting flight, the duty-free bag must be placed in your checked baggage before you board the connecting flight, or TSA officers at the connecting airport will confiscate it.
Keep your duty-free receipt and the sealed bag together. If an officer opens the bag or it becomes unsealed, you cannot bring the contents through security at a connecting airport.
International travel and different country rules
The 3.4-ounce rule applies at U.S. airports, but other countries have different rules. The European Union, Canada, Australia, and most other nations follow the same 3.4-ounce (100-milliliter) limit, but some countries are stricter or have additional restrictions.
If you are flying from the United States to another country, follow U.S. TSA rules at your departure airport. If you are connecting through another country, follow that country's rules at the connecting airport. If you are flying from another country to the United States, follow that country's rules at departure and U.S. rules at any connecting U.S. airports.
Check your airline's website and the TSA website for your specific route before you pack. Rules can change, and some airlines have stricter policies than the government minimum.
What happens if you bring a liquid that is too large
TSA officers will not allow oversized liquid containers through the security checkpoint. You have three options: leave the item behind, check it in your baggage if you have time to repack, or go back to the ticket counter and ask if you can check it.
If you discover the problem at the checkpoint, be honest and calm. Officers deal with this situation many times per day and will not penalize you. If you have time before your flight, you can step out of line, go back to the ticket counter, and add the item to your checked bag. If you do not have time, you will have to leave it behind or throw it away.
To avoid this situation, measure your containers before you pack. A container that looks small might hold more than 3.4 ounces. When in doubt, use a smaller container or pack the item in your checked bag instead.
Frequently Asked Questions
Can I bring a full water bottle through security?
No, you cannot bring a full water bottle through security because water is a liquid and the 3.4-ounce limit applies. You can bring an empty water bottle and fill it at a water fountain or refill station after you pass through security. Many airports have free water refill stations near the gates.
Does toothpaste count toward the 3.4-ounce limit?
Yes, toothpaste is classified as a gel and counts toward the limit. A standard travel-size tube of toothpaste is usually 0.85 ounces, so it fits easily. If you prefer a larger tube, pack it in your checked bag instead.
What if my medication is a liquid and I need more than 3.4 ounces?
Liquid medications in quantities larger than 3.4 ounces are allowed in carry-on bags, but you must declare them to TSA officers at the checkpoint. Bring the medication in its original labeled container with your name on it. Officers may need to open and inspect it, so be prepared for that.
Can I bring multiple small bottles that add up to more than 3.4 ounces?
No, the rule is that each individual container must be 3.4 ounces or smaller. You cannot bring ten 2-ounce bottles of shampoo in your carry-on, even though you could bring them in checked baggage. The limit is per container, not per type of item.
Are solid deodorants and bar soaps allowed in carry-on bags?
Yes, solid deodorants and bar soaps are not classified as liquids, gels, or aerosols, so they have no size limit and do not need to go in the quart bag. Spray deodorant and gel deodorant do count as aerosols and must follow the 3.4-ounce rule.